| Value | Category | Cases | |
|---|---|---|---|
| 1982 | 1 |
0.1%
|
|
| 1987 | 3 |
0.2%
|
|
| 1988 | 2 |
0.1%
|
|
| 1989 | 4 |
0.2%
|
|
| 1990 | 7 |
0.4%
|
|
| 1991 | 4 |
0.2%
|
|
| 1992 | 24 |
1.3%
|
|
| 1993 | 40 |
2.1%
|
|
| 1994 | 54 |
2.9%
|
|
| 1995 | 60 |
3.2%
|
|
| 1996 | 67 |
3.6%
|
|
| 1997 | 117 |
6.3%
|
|
| 1998 | 162 |
8.7%
|
|
| 1999 | 604 |
32.3%
|
|
| 2000 | 444 |
23.7%
|
|
| 9998 | don't know | 279 |
14.9%
|
| Sysmiss | 2117 |