| Value | Category | Cases | |
|---|---|---|---|
| 1980 | 2 | 
                                    
                                    1.9%
                                 | |
| 1982 | 1 | 
                                    
                                    0.9%
                                 | |
| 1983 | 1 | 
                                    
                                    0.9%
                                 | |
| 1985 | 1 | 
                                    
                                    0.9%
                                 | |
| 1988 | 2 | 
                                    
                                    1.9%
                                 | |
| 1989 | 6 | 
                                    
                                    5.7%
                                 | |
| 1990 | 4 | 
                                    
                                    3.8%
                                 | |
| 1991 | 5 | 
                                    
                                    4.7%
                                 | |
| 1992 | 3 | 
                                    
                                    2.8%
                                 | |
| 1993 | 5 | 
                                    
                                    4.7%
                                 | |
| 1994 | 11 | 
                                    
                                    10.4%
                                 | |
| 1995 | 17 | 
                                    
                                    16%
                                 | |
| 1996 | 18 | 
                                    
                                    17%
                                 | |
| 1997 | 26 | 
                                    
                                    24.5%
                                 | |
| 1998 | 4 | 
                                    
                                    3.8%
                                 | |
| Sysmiss | 3304 |