| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 5 |
7.8%
|
| 2010 | 1 |
1.6%
|
|
| 2014 | 1 |
1.6%
|
|
| 2015 | 4 |
6.3%
|
|
| 2016 | 2 |
3.1%
|
|
| 2017 | 14 |
21.9%
|
|
| 2018 | 34 |
53.1%
|
|
| 2019 | 3 |
4.7%
|
|
| Sysmiss | 301 |