| Value | Category | Cases | |
|---|---|---|---|
| -1 | missing | 0 |
0%
|
| 1 | very easy | 3533 |
7.3%
|
| 2 | easy | 8936 |
18.6%
|
| 3 | difficult | 4230 |
8.8%
|
| 4 | very difficult | 1665 |
3.5%
|
| 7 | not applicable | 29680 |
61.7%
|
| 8 | refused | 4 |
0%
|
| 9 | don't know | 36 |
0.1%
|