| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 0 |
0%
|
| 1997 | 1 |
14.3%
|
|
| 2008 | 1 |
14.3%
|
|
| 2011 | 2 |
28.6%
|
|
| 2018 | 1 |
14.3%
|
|
| 2020 | 2 |
28.6%
|
|
| Sysmiss | 395 |