| Value | Category | Cases | |
|---|---|---|---|
| -9 | don't know | 2 |
0.3%
|
| -8 | does not apply | 0 |
0%
|
| -7 | refused to answer | 1 |
0.1%
|
| 1967 | 1 |
0.1%
|
|
| 1971 | 1 |
0.1%
|
|
| 1975 | 2 |
0.3%
|
|
| 1980 | 2 |
0.3%
|
|
| 1981 | 1 |
0.1%
|
|
| 1982 | 2 |
0.3%
|
|
| 1983 | 1 |
0.1%
|
|
| 1984 | 1 |
0.1%
|
|
| 1987 | 1 |
0.1%
|
|
| 1989 | 3 |
0.4%
|
|
| 1990 | 4 |
0.5%
|
|
| 1991 | 1 |
0.1%
|
|
| 1992 | 1 |
0.1%
|
|
| 1993 | 4 |
0.5%
|
|
| 1994 | 8 |
1.1%
|
|
| 1995 | 4 |
0.5%
|
|
| 1996 | 8 |
1.1%
|
|
| 1997 | 3 |
0.4%
|
|
| 1998 | 12 |
1.6%
|
|
| 1999 | 14 |
1.9%
|
|
| 2000 | 24 |
3.2%
|
|
| 2001 | 24 |
3.2%
|
|
| 2002 | 24 |
3.2%
|
|
| 2003 | 47 |
6.2%
|
|
| 2004 | 36 |
4.8%
|
|
| 2005 | 72 |
9.5%
|
|
| 2006 | 166 |
22%
|
|
| 2007 | 165 |
21.8%
|
|
| 2008 | 121 |
16%
|