| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 4 |
0.5%
|
| -7 | Does not apply | 2 |
0.3%
|
| 0 | No obstacle | 144 |
18.9%
|
| 1 | Minor obstacle | 171 |
22.5%
|
| 2 | Moderate obstacle | 292 |
38.4%
|
| 3 | Major obstacle | 110 |
14.5%
|
| 4 | Very severe obstacle | 37 |
4.9%
|