| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 20 |
2.6%
|
| -7 | Does not apply | 4 |
0.5%
|
| 0 | No obstacle | 288 |
37.3%
|
| 1 | Minor obstacle | 174 |
22.5%
|
| 2 | Moderate obstacle | 186 |
24.1%
|
| 3 | Major obstacle | 72 |
9.3%
|
| 4 | Very severe obstacle | 28 |
3.6%
|