| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 2 |
2.6%
|
| 1990 | 1 |
1.3%
|
|
| 1995 | 1 |
1.3%
|
|
| 1997 | 1 |
1.3%
|
|
| 2000 | 4 |
5.3%
|
|
| 2002 | 1 |
1.3%
|
|
| 2003 | 1 |
1.3%
|
|
| 2004 | 4 |
5.3%
|
|
| 2005 | 1 |
1.3%
|
|
| 2006 | 2 |
2.6%
|
|
| 2007 | 1 |
1.3%
|
|
| 2008 | 2 |
2.6%
|
|
| 2009 | 2 |
2.6%
|
|
| 2010 | 5 |
6.6%
|
|
| 2011 | 1 |
1.3%
|
|
| 2012 | 6 |
7.9%
|
|
| 2013 | 5 |
6.6%
|
|
| 2014 | 4 |
5.3%
|
|
| 2015 | 1 |
1.3%
|
|
| 2016 | 6 |
7.9%
|
|
| 2017 | 14 |
18.4%
|
|
| 2018 | 7 |
9.2%
|
|
| 2019 | 4 |
5.3%
|
|
| Sysmiss | 44 |