| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 5 |
26.3%
|
| 2002 | 1 |
5.3%
|
|
| 2004 | 1 |
5.3%
|
|
| 2007 | 1 |
5.3%
|
|
| 2008 | 1 |
5.3%
|
|
| 2013 | 1 |
5.3%
|
|
| 2015 | 1 |
5.3%
|
|
| 2016 | 1 |
5.3%
|
|
| 2018 | 2 |
10.5%
|
|
| 2019 | 5 |
26.3%
|
|
| Sysmiss | 190 |