| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 4 |
0.5%
|
| -7 | Does not apply | 78 |
10.7%
|
| 0 | No obstacle | 346 |
47.5%
|
| 1 | Minor obstacle | 110 |
15.1%
|
| 2 | Moderate obstacle | 104 |
14.3%
|
| 3 | Major obstacle | 34 |
4.7%
|
| 4 | Very severe obstacle | 53 |
7.3%
|