| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 58 |
16.2%
|
| 2005 | 1 |
0.3%
|
|
| 2007 | 1 |
0.3%
|
|
| 2009 | 1 |
0.3%
|
|
| 2010 | 3 |
0.8%
|
|
| 2011 | 2 |
0.6%
|
|
| 2012 | 4 |
1.1%
|
|
| 2013 | 7 |
2%
|
|
| 2014 | 15 |
4.2%
|
|
| 2015 | 43 |
12%
|
|
| 2016 | 72 |
20.2%
|
|
| 2017 | 88 |
24.6%
|
|
| 2018 | 62 |
17.4%
|
|
| Sysmiss | 415 |