| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 0 |
0%
|
| 2009 | 2 |
14.3%
|
|
| 2010 | 2 |
14.3%
|
|
| 2011 | 3 |
21.4%
|
|
| 2013 | 1 |
7.1%
|
|
| 2014 | 2 |
14.3%
|
|
| 2016 | 3 |
21.4%
|
|
| 2018 | 1 |
7.1%
|
|
| Sysmiss | 121 |