| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 9 |
0.9%
|
| -7 | Does not apply | 21 |
2.1%
|
| 0 | No obstacle | 723 |
72.4%
|
| 1 | Minor obstacle | 102 |
10.2%
|
| 2 | Moderate obstacle | 64 |
6.4%
|
| 3 | Major obstacle | 56 |
5.6%
|
| 4 | Very severe obstacle | 23 |
2.3%
|