| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 3 |
0.4%
|
| -7 | Does not apply | 1 |
0.1%
|
| 0 | No obstacle | 413 |
57.9%
|
| 1 | Minor obstacle | 199 |
27.9%
|
| 2 | Moderate obstacle | 60 |
8.4%
|
| 3 | Major obstacle | 30 |
4.2%
|
| 4 | Very severe obstacle | 7 |
1%
|