| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 13 |
1%
|
| -7 | Does not apply | 4 |
0.3%
|
| 0 | No obstacle | 432 |
32.7%
|
| 1 | Minor obstacle | 338 |
25.5%
|
| 2 | Moderate obstacle | 364 |
27.5%
|
| 3 | Major obstacle | 139 |
10.5%
|
| 4 | Very severe obstacle | 33 |
2.5%
|