| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 1 |
0.2%
|
| -7 | Does not apply | 1 |
0.2%
|
| 0 | No obstacle | 108 |
18%
|
| 1 | Minor obstacle | 152 |
25.3%
|
| 2 | Moderate obstacle | 204 |
33.9%
|
| 3 | Major obstacle | 120 |
20%
|
| 4 | Very severe obstacle | 15 |
2.5%
|