| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 1 |
0.2%
|
| -7 | Does not apply | 2 |
0.5%
|
| 0 | No obstacle | 228 |
56.7%
|
| 1 | Minor obstacle | 82 |
20.4%
|
| 2 | Moderate obstacle | 52 |
12.9%
|
| 3 | Major obstacle | 31 |
7.7%
|
| 4 | Very severe obstacle | 6 |
1.5%
|