| Value | Category | Cases | |
|---|---|---|---|
| 1985 | 1 | 
                                    
                                    0.5%
                                 | |
| 1992 | 3 | 
                                    
                                    1.4%
                                 | |
| 1993 | 1 | 
                                    
                                    0.5%
                                 | |
| 1994 | 4 | 
                                    
                                    1.9%
                                 | |
| 1995 | 2 | 
                                    
                                    0.9%
                                 | |
| 1996 | 1 | 
                                    
                                    0.5%
                                 | |
| 1997 | 17 | 
                                    
                                    8.1%
                                 | |
| 1998 | 27 | 
                                    
                                    12.8%
                                 | |
| 1999 | 41 | 
                                    
                                    19.4%
                                 | |
| 2000 | 33 | 
                                    
                                    15.6%
                                 | |
| 2001 | 50 | 
                                    
                                    23.7%
                                 | |
| 2002 | 31 | 
                                    
                                    14.7%
                                 | |
| Sysmiss | 16 |