| Value | Category | Cases | |
|---|---|---|---|
| 1968 | 1 | 
                                    
                                    0%
                                 | |
| 1969 | 45 | 
                                    
                                    2.1%
                                 | |
| 1970 | 41 | 
                                    
                                    1.9%
                                 | |
| 1971 | 28 | 
                                    
                                    1.3%
                                 | |
| 1972 | 39 | 
                                    
                                    1.8%
                                 | |
| 1973 | 30 | 
                                    
                                    1.4%
                                 | |
| 1974 | 38 | 
                                    
                                    1.8%
                                 | |
| 1975 | 47 | 
                                    
                                    2.2%
                                 | |
| 1976 | 36 | 
                                    
                                    1.7%
                                 | |
| 1977 | 42 | 
                                    
                                    2%
                                 | |
| 1978 | 32 | 
                                    
                                    1.5%
                                 | |
| 1979 | 65 | 
                                    
                                    3%
                                 | |
| 1980 | 57 | 
                                    
                                    2.6%
                                 | |
| 1981 | 39 | 
                                    
                                    1.8%
                                 | |
| 1982 | 56 | 
                                    
                                    2.6%
                                 | |
| 1983 | 41 | 
                                    
                                    1.9%
                                 | |
| 1984 | 63 | 
                                    
                                    2.9%
                                 | |
| 1985 | 54 | 
                                    
                                    2.5%
                                 | |
| 1986 | 62 | 
                                    
                                    2.9%
                                 | |
| 1987 | 87 | 
                                    
                                    4%
                                 | |
| 1988 | 54 | 
                                    
                                    2.5%
                                 | |
| 1989 | 63 | 
                                    
                                    2.9%
                                 | |
| 1990 | 77 | 
                                    
                                    3.6%
                                 | |
| 1991 | 71 | 
                                    
                                    3.3%
                                 | |
| 1992 | 82 | 
                                    
                                    3.8%
                                 | |
| 1993 | 61 | 
                                    
                                    2.8%
                                 | |
| 1994 | 64 | 
                                    
                                    3%
                                 | |
| 1995 | 74 | 
                                    
                                    3.4%
                                 | |
| 1996 | 88 | 
                                    
                                    4.1%
                                 | |
| 1997 | 74 | 
                                    
                                    3.4%
                                 | |
| 1998 | 82 | 
                                    
                                    3.8%
                                 | |
| 1999 | 82 | 
                                    
                                    3.8%
                                 | |
| 2000 | 90 | 
                                    
                                    4.2%
                                 | |
| 2001 | 77 | 
                                    
                                    3.6%
                                 | |
| 2002 | 73 | 
                                    
                                    3.4%
                                 | |
| 2003 | 67 | 
                                    
                                    3.1%
                                 | |
| 9998 | DK | 1 | 
                                    
                                    0%
                                 | 
| Sysmiss | 70 | 
                                    
                                    3.3%
                                 |