| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 8 |
0.5%
|
| -7 | Does not apply | 161 |
9.3%
|
| 0 | No obstacle | 651 |
37.7%
|
| 1 | Minor obstacle | 341 |
19.8%
|
| 2 | Moderate obstacle | 278 |
16.1%
|
| 3 | Major obstacle | 175 |
10.1%
|
| 4 | Very severe obstacle | 111 |
6.4%
|