| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 3 |
0.5%
|
| -7 | Does not apply | 5 |
0.8%
|
| 0 | No obstacle | 82 |
13.7%
|
| 1 | Minor obstacle | 106 |
17.7%
|
| 2 | Moderate obstacle | 120 |
20.1%
|
| 3 | Major obstacle | 188 |
31.4%
|
| 4 | Very severe obstacle | 94 |
15.7%
|