| Value | Category | Cases | |
|---|---|---|---|
| 1968 | 47 | 
                                    
                                    0.3%
                                 | |
| 1969 | 108 | 
                                    
                                    0.8%
                                 | |
| 1970 | 178 | 
                                    
                                    1.2%
                                 | |
| 1971 | 143 | 
                                    
                                    1%
                                 | |
| 1972 | 184 | 
                                    
                                    1.3%
                                 | |
| 1973 | 201 | 
                                    
                                    1.4%
                                 | |
| 1974 | 190 | 
                                    
                                    1.3%
                                 | |
| 1975 | 217 | 
                                    
                                    1.5%
                                 | |
| 1976 | 222 | 
                                    
                                    1.6%
                                 | |
| 1977 | 251 | 
                                    
                                    1.8%
                                 | |
| 1978 | 316 | 
                                    
                                    2.2%
                                 | |
| 1979 | 270 | 
                                    
                                    1.9%
                                 | |
| 1980 | 342 | 
                                    
                                    2.4%
                                 | |
| 1981 | 392 | 
                                    
                                    2.7%
                                 | |
| 1982 | 388 | 
                                    
                                    2.7%
                                 | |
| 1983 | 384 | 
                                    
                                    2.7%
                                 | |
| 1984 | 349 | 
                                    
                                    2.4%
                                 | |
| 1985 | 405 | 
                                    
                                    2.8%
                                 | |
| 1986 | 370 | 
                                    
                                    2.6%
                                 | |
| 1987 | 457 | 
                                    
                                    3.2%
                                 | |
| 1988 | 500 | 
                                    
                                    3.5%
                                 | |
| 1989 | 401 | 
                                    
                                    2.8%
                                 | |
| 1990 | 419 | 
                                    
                                    2.9%
                                 | |
| 1991 | 435 | 
                                    
                                    3%
                                 | |
| 1992 | 561 | 
                                    
                                    3.9%
                                 | |
| 1993 | 515 | 
                                    
                                    3.6%
                                 | |
| 1994 | 620 | 
                                    
                                    4.3%
                                 | |
| 1995 | 486 | 
                                    
                                    3.4%
                                 | |
| 1996 | 481 | 
                                    
                                    3.4%
                                 | |
| 1997 | 515 | 
                                    
                                    3.6%
                                 | |
| 1998 | 551 | 
                                    
                                    3.9%
                                 | |
| 1999 | 614 | 
                                    
                                    4.3%
                                 | |
| 2000 | 694 | 
                                    
                                    4.9%
                                 | |
| 2001 | 574 | 
                                    
                                    4%
                                 | |
| 2002 | 673 | 
                                    
                                    4.7%
                                 | |
| 2003 | 180 | 
                                    
                                    1.3%
                                 | |
| 9998 | DK | 6 | 
                                    
                                    0%
                                 | 
| 9999 | NO RESPONSE | 1 | 
                                    
                                    0%
                                 | 
| Sysmiss | 657 | 
                                    
                                    4.6%
                                 |