| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 2 |
0.2%
|
| -7 | Does not apply | 11 |
0.9%
|
| 0 | No obstacle | 434 |
35.7%
|
| 1 | Minor obstacle | 218 |
17.9%
|
| 2 | Moderate obstacle | 369 |
30.3%
|
| 3 | Major obstacle | 135 |
11.1%
|
| 4 | Very severe obstacle | 47 |
3.9%
|