| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 1 |
0.3%
|
| -7 | Does not apply | 22 |
5.6%
|
| 0 | No obstacle | 146 |
37.2%
|
| 1 | Minor obstacle | 114 |
29.1%
|
| 2 | Moderate obstacle | 66 |
16.8%
|
| 3 | Major obstacle | 39 |
9.9%
|
| 4 | Very severe obstacle | 4 |
1%
|