| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 24 |
8.4%
|
| 1950 | 2 |
0.7%
|
|
| 1960 | 3 |
1%
|
|
| 1968 | 3 |
1%
|
|
| 1970 | 5 |
1.7%
|
|
| 1971 | 1 |
0.3%
|
|
| 1972 | 2 |
0.7%
|
|
| 1973 | 1 |
0.3%
|
|
| 1975 | 4 |
1.4%
|
|
| 1976 | 2 |
0.7%
|
|
| 1979 | 3 |
1%
|
|
| 1980 | 11 |
3.8%
|
|
| 1983 | 1 |
0.3%
|
|
| 1984 | 1 |
0.3%
|
|
| 1985 | 7 |
2.4%
|
|
| 1986 | 1 |
0.3%
|
|
| 1987 | 1 |
0.3%
|
|
| 1988 | 1 |
0.3%
|
|
| 1989 | 1 |
0.3%
|
|
| 1990 | 24 |
8.4%
|
|
| 1991 | 3 |
1%
|
|
| 1992 | 4 |
1.4%
|
|
| 1993 | 2 |
0.7%
|
|
| 1994 | 5 |
1.7%
|
|
| 1995 | 10 |
3.5%
|
|
| 1996 | 4 |
1.4%
|
|
| 1997 | 3 |
1%
|
|
| 1998 | 4 |
1.4%
|
|
| 1999 | 3 |
1%
|
|
| 2000 | 32 |
11.1%
|
|
| 2001 | 6 |
2.1%
|
|
| 2002 | 4 |
1.4%
|
|
| 2003 | 5 |
1.7%
|
|
| 2004 | 2 |
0.7%
|
|
| 2005 | 12 |
4.2%
|
|
| 2006 | 6 |
2.1%
|
|
| 2007 | 6 |
2.1%
|
|
| 2008 | 7 |
2.4%
|
|
| 2009 | 4 |
1.4%
|
|
| 2010 | 16 |
5.6%
|
|
| 2011 | 7 |
2.4%
|
|
| 2012 | 8 |
2.8%
|
|
| 2013 | 6 |
2.1%
|
|
| 2014 | 4 |
1.4%
|
|
| 2015 | 14 |
4.9%
|
|
| 2016 | 7 |
2.4%
|
|
| 2017 | 4 |
1.4%
|
|
| 2018 | 1 |
0.3%
|
|
| Sysmiss | 473 |