| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 1 |
20%
|
| 1991 | 1 |
20%
|
|
| 2008 | 1 |
20%
|
|
| 2018 | 1 |
20%
|
|
| 2019 | 1 |
20%
|
|
| Sysmiss | 92 |