| Value | Category | Cases | |
|---|---|---|---|
| 1988 | 1 | 
                                    
                                    0.5%
                                 | |
| 1994 | 18 | 
                                    
                                    8.8%
                                 | |
| 1995 | 10 | 
                                    
                                    4.9%
                                 | |
| 1996 | 11 | 
                                    
                                    5.4%
                                 | |
| 1997 | 20 | 
                                    
                                    9.8%
                                 | |
| 1998 | 18 | 
                                    
                                    8.8%
                                 | |
| 1999 | 21 | 
                                    
                                    10.3%
                                 | |
| 2000 | 22 | 
                                    
                                    10.8%
                                 | |
| 2001 | 48 | 
                                    
                                    23.5%
                                 | |
| 2002 | 35 | 
                                    
                                    17.2%
                                 | |
| Sysmiss | 248 |