| Value | Category | Cases | |
|---|---|---|---|
| 1995 | 6 | 
                                    
                                    0.3%
                                 | |
| 1996 | 257 | 
                                    
                                    12.3%
                                 | |
| 1997 | 299 | 
                                    
                                    14.3%
                                 | |
| 1998 | 391 | 
                                    
                                    18.7%
                                 | |
| 1999 | 572 | 
                                    
                                    27.4%
                                 | |
| 2000 | 560 | 
                                    
                                    26.8%
                                 | |
| 9997 | inconsistent | 1 | 
                                    
                                    0%
                                 | 
| 9998 | dk | 0 | 
                                    
                                    0%
                                 | 
| Sysmiss | 12860 |