| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 4 |
3.5%
|
| 1982 | 1 |
0.9%
|
|
| 1990 | 1 |
0.9%
|
|
| 1992 | 1 |
0.9%
|
|
| 1997 | 1 |
0.9%
|
|
| 1998 | 1 |
0.9%
|
|
| 2003 | 1 |
0.9%
|
|
| 2004 | 2 |
1.7%
|
|
| 2006 | 2 |
1.7%
|
|
| 2007 | 2 |
1.7%
|
|
| 2008 | 4 |
3.5%
|
|
| 2009 | 3 |
2.6%
|
|
| 2010 | 4 |
3.5%
|
|
| 2011 | 2 |
1.7%
|
|
| 2012 | 3 |
2.6%
|
|
| 2013 | 2 |
1.7%
|
|
| 2014 | 9 |
7.8%
|
|
| 2015 | 6 |
5.2%
|
|
| 2016 | 8 |
7%
|
|
| 2017 | 22 |
19.1%
|
|
| 2018 | 36 |
31.3%
|
|
| Sysmiss | 127 |