            

                      1993   2                                                                                      
        
              
                                             
                                                   1990                                                                                                                                                                     
            
                                                                                                             
                               
                                         
                           
           
                            
                                                                           
                                                                  
                                  
                  
                          
                                                                                                     
                 1987                                     
                      50           50                                                                                                                                                         1987   7                   
                                      
                                                      
                                                            
                                                                                                                                                                     
                                                                                                                                                                
                                                                                                                                                                    
                                                                                                                                     
                                                                                                                                                                               50                            40                                                                                                                                                                                                                  
                   
                                                           
              
                   
                                                                                                                                                   
                                      
                                                                                                                                                                                                                                                          
                                                                                                                                                                                                        
                       
                                                                                                                                                                                                                        
                                
                                                                                              
                           
                                                      
         
            
                          
                                                                            
              30                        
                     30                                                                                               
                         
                                                                                                  
                                                                    
                                                                                                     