| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 2 |
0.2%
|
| -7 | Does not apply | 0 |
0%
|
| 0 | No obstacle | 444 |
44.5%
|
| 1 | Minor obstacle | 246 |
24.6%
|
| 2 | Moderate obstacle | 154 |
15.4%
|
| 3 | Major obstacle | 128 |
12.8%
|
| 4 | Very severe obstacle | 24 |
2.4%
|