| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 4 |
0.5%
|
| -7 | Does not apply | 5 |
0.7%
|
| 0 | No obstacle | 186 |
24.5%
|
| 1 | Minor obstacle | 194 |
25.5%
|
| 2 | Moderate obstacle | 255 |
33.6%
|
| 3 | Major obstacle | 89 |
11.7%
|
| 4 | Very severe obstacle | 27 |
3.6%
|