| Value | Category | Cases | |
|---|---|---|---|
| 1982 | 1 |
0.1%
|
|
| 1987 | 2 |
0.2%
|
|
| 1988 | 1 |
0.1%
|
|
| 1989 | 3 |
0.2%
|
|
| 1990 | 6 |
0.5%
|
|
| 1991 | 3 |
0.2%
|
|
| 1992 | 15 |
1.2%
|
|
| 1993 | 28 |
2.2%
|
|
| 1994 | 36 |
2.8%
|
|
| 1995 | 42 |
3.3%
|
|
| 1996 | 39 |
3.1%
|
|
| 1997 | 70 |
5.5%
|
|
| 1998 | 112 |
8.8%
|
|
| 1999 | 425 |
33.3%
|
|
| 2000 | 303 |
23.8%
|
|
| 9998 | don't know | 189 |
14.8%
|
| Sysmiss | 5480 |