| Value | Category |
|---|---|
| -9 | Don't know |
| -8 | Refused |
| 1 | Possible to achieve without much effort |
| 2 | Possible to achieve with some effort |
| 3 | Possible to achieve with normal amount of effort |
| 4 | Possible to achieve with more than normal effort |
| 5 | Only possible to achieve with extraordinary effort |
| Sysmiss |