| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 1 |
2.8%
|
| 1994 | 1 |
2.8%
|
|
| 2000 | 1 |
2.8%
|
|
| 2005 | 2 |
5.6%
|
|
| 2008 | 1 |
2.8%
|
|
| 2009 | 1 |
2.8%
|
|
| 2012 | 1 |
2.8%
|
|
| 2013 | 2 |
5.6%
|
|
| 2014 | 2 |
5.6%
|
|
| 2015 | 3 |
8.3%
|
|
| 2016 | 8 |
22.2%
|
|
| 2017 | 10 |
27.8%
|
|
| 2018 | 3 |
8.3%
|
|
| Sysmiss | 518 |