| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 2 |
0.2%
|
| -7 | Does not apply | 14 |
1.5%
|
| 0 | No obstacle | 178 |
18.8%
|
| 1 | Minor obstacle | 248 |
26.2%
|
| 2 | Moderate obstacle | 277 |
29.3%
|
| 3 | Major obstacle | 150 |
15.8%
|
| 4 | Very severe obstacle | 78 |
8.2%
|