| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 4 |
0.3%
|
| -7 | Does not apply | 4 |
0.3%
|
| 0 | No obstacle | 139 |
10.5%
|
| 1 | Minor obstacle | 252 |
19%
|
| 2 | Moderate obstacle | 498 |
37.6%
|
| 3 | Major obstacle | 266 |
20.1%
|
| 4 | Very severe obstacle | 160 |
12.1%
|