| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 3 |
2%
|
| 1974 | 1 |
0.7%
|
|
| 1978 | 1 |
0.7%
|
|
| 1986 | 1 |
0.7%
|
|
| 1990 | 1 |
0.7%
|
|
| 1994 | 1 |
0.7%
|
|
| 1995 | 4 |
2.6%
|
|
| 1996 | 2 |
1.3%
|
|
| 1999 | 4 |
2.6%
|
|
| 2000 | 5 |
3.3%
|
|
| 2001 | 2 |
1.3%
|
|
| 2002 | 2 |
1.3%
|
|
| 2003 | 1 |
0.7%
|
|
| 2004 | 4 |
2.6%
|
|
| 2005 | 3 |
2%
|
|
| 2006 | 2 |
1.3%
|
|
| 2007 | 1 |
0.7%
|
|
| 2008 | 5 |
3.3%
|
|
| 2009 | 2 |
1.3%
|
|
| 2010 | 10 |
6.6%
|
|
| 2011 | 5 |
3.3%
|
|
| 2012 | 10 |
6.6%
|
|
| 2013 | 6 |
3.9%
|
|
| 2014 | 7 |
4.6%
|
|
| 2015 | 21 |
13.8%
|
|
| 2016 | 16 |
10.5%
|
|
| 2017 | 25 |
16.4%
|
|
| 2018 | 7 |
4.6%
|
|
| Sysmiss | 402 |