| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 1 |
0.1%
|
| -7 | Does not apply | 5 |
0.4%
|
| 0 | No obstacle | 307 |
25.2%
|
| 1 | Minor obstacle | 172 |
14.1%
|
| 2 | Moderate obstacle | 408 |
33.6%
|
| 3 | Major obstacle | 241 |
19.8%
|
| 4 | Very severe obstacle | 82 |
6.7%
|