| Value | Category | Cases | |
|---|---|---|---|
| 1996 | 100 | 
                                                                 
                                    
                                    6.2%
                                 
                                                             | 
                                                        
                    |
| 1997 | 169 | 
                                                                 
                                    
                                    10.5%
                                 
                                                             | 
                                                        
                    |
| 1998 | 290 | 
                                                                 
                                    
                                    18%
                                 
                                                             | 
                                                        
                    |
| 1999 | 511 | 
                                                                 
                                    
                                    31.8%
                                 
                                                             | 
                                                        
                    |
| 2000 | 537 | 
                                                                 
                                    
                                    33.4%
                                 
                                                             | 
                                                        
                    |
| 9997 | inconsistent | 1 | 
                                                                 
                                    
                                    0.1%
                                 
                                                             | 
                                                        
                    
| 9998 | dk | 0 | 
                                                                 
                                    
                                    0%
                                 
                                                             | 
                                                        
                    
| Sysmiss | 5147 |