| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 1 |
0.2%
|
| -7 | Does not apply | 8 |
1.4%
|
| 0 | No obstacle | 316 |
53.4%
|
| 1 | Minor obstacle | 64 |
10.8%
|
| 2 | Moderate obstacle | 81 |
13.7%
|
| 3 | Major obstacle | 80 |
13.5%
|
| 4 | Very severe obstacle | 42 |
7.1%
|