| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 3 |
0.4%
|
| -7 | Does not apply | 4 |
0.5%
|
| 0 | No obstacle | 406 |
55.7%
|
| 1 | Minor obstacle | 137 |
18.8%
|
| 2 | Moderate obstacle | 96 |
13.2%
|
| 3 | Major obstacle | 30 |
4.1%
|
| 4 | Very severe obstacle | 53 |
7.3%
|