| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 64 |
3.8%
|
| -7 | Does not apply | 28 |
1.7%
|
| 0 | No obstacle | 106 |
6.4%
|
| 1 | Minor obstacle | 129 |
7.8%
|
| 2 | Moderate obstacle | 342 |
20.6%
|
| 3 | Major obstacle | 452 |
27.2%
|
| 4 | Very severe obstacle | 542 |
32.6%
|