| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 17 |
42.5%
|
| 2013 | 1 |
2.5%
|
|
| 2016 | 3 |
7.5%
|
|
| 2019 | 4 |
10%
|
|
| 2020 | 11 |
27.5%
|
|
| 2021 | 2 |
5%
|
|
| 2022 | 1 |
2.5%
|
|
| 2023 | 1 |
2.5%
|
|
| Sysmiss | 1719 |