| Value | Category | Cases | |
|---|---|---|---|
| 0 | 0. No difficulty | 999 |
14.2%
|
| 1 | 1. Minor difficulty | 5521 |
78.2%
|
| 2 | 2. Big difficulty | 315 |
4.5%
|
| 3 | 3. Not applicable | 222 |
3.1%
|