| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 4 |
0.4%
|
| -7 | Does not apply | 2 |
0.2%
|
| 0 | No obstacle | 258 |
26.1%
|
| 1 | Minor obstacle | 209 |
21.2%
|
| 2 | Moderate obstacle | 327 |
33.1%
|
| 3 | Major obstacle | 130 |
13.2%
|
| 4 | Very severe obstacle | 57 |
5.8%
|