| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 0 |
0%
|
| -7 | Does not apply | 2 |
0.6%
|
| 0 | No obstacle | 267 |
85.9%
|
| 1 | Minor obstacle | 16 |
5.1%
|
| 2 | Moderate obstacle | 15 |
4.8%
|
| 3 | Major obstacle | 10 |
3.2%
|
| 4 | Very severe obstacle | 1 |
0.3%
|