| Value | Category | Cases | |
|---|---|---|---|
| -2 | don't know | 93 |
40.4%
|
| 1960 | 1 |
0.4%
|
|
| 1970 | 2 |
0.9%
|
|
| 1973 | 1 |
0.4%
|
|
| 1975 | 3 |
1.3%
|
|
| 1980 | 7 |
3%
|
|
| 1982 | 1 |
0.4%
|
|
| 1983 | 3 |
1.3%
|
|
| 1984 | 5 |
2.2%
|
|
| 1985 | 13 |
5.7%
|
|
| 1986 | 5 |
2.2%
|
|
| 1987 | 8 |
3.5%
|
|
| 1988 | 9 |
3.9%
|
|
| 1989 | 4 |
1.7%
|
|
| 1990 | 11 |
4.8%
|
|
| 1991 | 4 |
1.7%
|
|
| 1992 | 7 |
3%
|
|
| 1993 | 2 |
0.9%
|
|
| 1995 | 5 |
2.2%
|
|
| 1996 | 2 |
0.9%
|
|
| 1997 | 1 |
0.4%
|
|
| 1998 | 6 |
2.6%
|
|
| 1999 | 1 |
0.4%
|
|
| 2000 | 7 |
3%
|
|
| 2001 | 1 |
0.4%
|
|
| 2002 | 4 |
1.7%
|
|
| 2003 | 3 |
1.3%
|
|
| 2005 | 1 |
0.4%
|
|
| 2006 | 1 |
0.4%
|
|
| 2007 | 3 |
1.3%
|
|
| 2008 | 6 |
2.6%
|
|
| 2009 | 10 |
4.3%
|
|
| Sysmiss | 819 |