| Value | Category | Cases | |
|---|---|---|---|
| 1 | very easy | 40 |
2.5%
|
| 2 | easy | 236 |
14.7%
|
| 3 | don't know | 1080 |
67.1%
|
| 4 | hard | 237 |
14.7%
|
| 5 | very hard | 16 |
1%
|