| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 2 |
0.6%
|
| -7 | Does not apply | 1 |
0.3%
|
| 0 | No obstacle | 32 |
9.3%
|
| 1 | Minor obstacle | 24 |
7%
|
| 2 | Moderate obstacle | 27 |
7.8%
|
| 3 | Major obstacle | 80 |
23.2%
|
| 4 | Very severe obstacle | 179 |
51.9%
|