| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 16 |
11.6%
|
| 1936 | 1 |
0.7%
|
|
| 1975 | 1 |
0.7%
|
|
| 1978 | 2 |
1.4%
|
|
| 1980 | 1 |
0.7%
|
|
| 1982 | 1 |
0.7%
|
|
| 1990 | 2 |
1.4%
|
|
| 1991 | 3 |
2.2%
|
|
| 1992 | 1 |
0.7%
|
|
| 1993 | 2 |
1.4%
|
|
| 1994 | 4 |
2.9%
|
|
| 1995 | 4 |
2.9%
|
|
| 1996 | 4 |
2.9%
|
|
| 1997 | 2 |
1.4%
|
|
| 1998 | 5 |
3.6%
|
|
| 1999 | 5 |
3.6%
|
|
| 2000 | 11 |
8%
|
|
| 2001 | 7 |
5.1%
|
|
| 2002 | 2 |
1.4%
|
|
| 2003 | 1 |
0.7%
|
|
| 2004 | 4 |
2.9%
|
|
| 2005 | 5 |
3.6%
|
|
| 2006 | 7 |
5.1%
|
|
| 2007 | 7 |
5.1%
|
|
| 2008 | 2 |
1.4%
|
|
| 2009 | 5 |
3.6%
|
|
| 2010 | 8 |
5.8%
|
|
| 2011 | 4 |
2.9%
|
|
| 2012 | 3 |
2.2%
|
|
| 2013 | 3 |
2.2%
|
|
| 2014 | 2 |
1.4%
|
|
| 2015 | 4 |
2.9%
|
|
| 2016 | 7 |
5.1%
|
|
| 2017 | 2 |
1.4%
|
|
| Sysmiss | 222 |