| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 1 |
0.3%
|
| -7 | Does not apply | 4 |
1.1%
|
| 0 | No obstacle | 14 |
3.9%
|
| 1 | Minor obstacle | 18 |
5%
|
| 2 | Moderate obstacle | 66 |
18.3%
|
| 3 | Major obstacle | 163 |
45.3%
|
| 4 | Very severe obstacle | 94 |
26.1%
|