| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 6 |
0.2%
|
| -7 | Does not apply | 33 |
1.2%
|
| 0 | No obstacle | 1418 |
52.6%
|
| 1 | Minor obstacle | 614 |
22.8%
|
| 2 | Moderate obstacle | 385 |
14.3%
|
| 3 | Major obstacle | 171 |
6.3%
|
| 4 | Very severe obstacle | 70 |
2.6%
|