| Value | Category | Cases | |
|---|---|---|---|
| -2 | don't know | 38 |
34.9%
|
| 1970 | 2 |
1.8%
|
|
| 1974 | 1 |
0.9%
|
|
| 1980 | 3 |
2.8%
|
|
| 1984 | 1 |
0.9%
|
|
| 1985 | 8 |
7.3%
|
|
| 1986 | 4 |
3.7%
|
|
| 1987 | 3 |
2.8%
|
|
| 1988 | 1 |
0.9%
|
|
| 1989 | 6 |
5.5%
|
|
| 1990 | 9 |
8.3%
|
|
| 1991 | 4 |
3.7%
|
|
| 1993 | 1 |
0.9%
|
|
| 1994 | 1 |
0.9%
|
|
| 1995 | 1 |
0.9%
|
|
| 1996 | 3 |
2.8%
|
|
| 1997 | 1 |
0.9%
|
|
| 1998 | 1 |
0.9%
|
|
| 1999 | 1 |
0.9%
|
|
| 2000 | 4 |
3.7%
|
|
| 2002 | 1 |
0.9%
|
|
| 2003 | 1 |
0.9%
|
|
| 2006 | 4 |
3.7%
|
|
| 2007 | 2 |
1.8%
|
|
| 2008 | 4 |
3.7%
|
|
| 2009 | 4 |
3.7%
|
|
| Sysmiss | 940 |