| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 185 |
39.4%
|
| 1947 | 1 |
0.2%
|
|
| 1950 | 1 |
0.2%
|
|
| 1952 | 1 |
0.2%
|
|
| 1962 | 1 |
0.2%
|
|
| 1972 | 1 |
0.2%
|
|
| 1975 | 2 |
0.4%
|
|
| 1976 | 1 |
0.2%
|
|
| 1977 | 1 |
0.2%
|
|
| 1978 | 1 |
0.2%
|
|
| 1979 | 1 |
0.2%
|
|
| 1982 | 1 |
0.2%
|
|
| 1983 | 1 |
0.2%
|
|
| 1984 | 2 |
0.4%
|
|
| 1985 | 3 |
0.6%
|
|
| 1987 | 2 |
0.4%
|
|
| 1988 | 2 |
0.4%
|
|
| 1989 | 2 |
0.4%
|
|
| 1990 | 5 |
1.1%
|
|
| 1991 | 2 |
0.4%
|
|
| 1992 | 5 |
1.1%
|
|
| 1993 | 1 |
0.2%
|
|
| 1994 | 4 |
0.9%
|
|
| 1995 | 6 |
1.3%
|
|
| 1996 | 5 |
1.1%
|
|
| 1998 | 13 |
2.8%
|
|
| 1999 | 9 |
1.9%
|
|
| 2000 | 16 |
3.4%
|
|
| 2001 | 11 |
2.3%
|
|
| 2002 | 9 |
1.9%
|
|
| 2003 | 8 |
1.7%
|
|
| 2004 | 7 |
1.5%
|
|
| 2005 | 6 |
1.3%
|
|
| 2006 | 10 |
2.1%
|
|
| 2007 | 6 |
1.3%
|
|
| 2008 | 11 |
2.3%
|
|
| 2009 | 19 |
4.1%
|
|
| 2010 | 27 |
5.8%
|
|
| 2011 | 9 |
1.9%
|
|
| 2012 | 16 |
3.4%
|
|
| 2013 | 8 |
1.7%
|
|
| 2014 | 10 |
2.1%
|
|
| 2015 | 6 |
1.3%
|
|
| 2016 | 9 |
1.9%
|
|
| 2017 | 16 |
3.4%
|
|
| 2018 | 6 |
1.3%
|
|
| Sysmiss | 627 |