| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 1 |
0.3%
|
| -7 | Does not apply | 7 |
2%
|
| 0 | No obstacle | 95 |
26.6%
|
| 1 | Minor obstacle | 55 |
15.4%
|
| 2 | Moderate obstacle | 90 |
25.2%
|
| 3 | Major obstacle | 82 |
23%
|
| 4 | Very severe obstacle | 27 |
7.6%
|