| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 3 |
0.5%
|
| -7 | Does not apply | 13 |
2.2%
|
| 0 | No obstacle | 137 |
22.8%
|
| 1 | Minor obstacle | 101 |
16.8%
|
| 2 | Moderate obstacle | 200 |
33.3%
|
| 3 | Major obstacle | 97 |
16.1%
|
| 4 | Very severe obstacle | 50 |
8.3%
|