| Value | Category | Cases | |
|---|---|---|---|
| -2 | Refusal to answer | 9 |
1.4%
|
| -1 | Don't know | 9 |
1.4%
|
| 0 | 20 |
3.1%
|
|
| 1952 | 1 |
0.2%
|
|
| 1990 | 2 |
0.3%
|
|
| 1991 | 7 |
1.1%
|
|
| 1992 | 12 |
1.9%
|
|
| 1993 | 15 |
2.3%
|
|
| 1994 | 22 |
3.4%
|
|
| 1995 | 21 |
3.3%
|
|
| 1996 | 16 |
2.5%
|
|
| 1997 | 35 |
5.4%
|
|
| 1998 | 39 |
6.1%
|
|
| 1999 | 51 |
7.9%
|
|
| 2000 | 105 |
16.3%
|
|
| 2001 | 280 |
43.5%
|
|
| Sysmiss | 921 |