| Value | Category | Cases | |
|---|---|---|---|
| 1996 | 3 | 
                                                                 
                                    
                                    11.5%
                                 
                                                             | 
                                                        
                    |
| 1997 | 16 | 
                                                                 
                                    
                                    61.5%
                                 
                                                             | 
                                                        
                    |
| 1998 | 4 | 
                                                                 
                                    
                                    15.4%
                                 
                                                             | 
                                                        
                    |
| 1999 | 3 | 
                                                                 
                                    
                                    11.5%
                                 
                                                             | 
                                                        
                    |
| 9997 | inconsistent | 0 | 
                                                                 
                                    
                                    0%
                                 
                                                             | 
                                                        
                    
| 9998 | dk | 0 | 
                                                                 
                                    
                                    0%
                                 
                                                             | 
                                                        
                    
| Sysmiss | 6729 |