| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 2 |
0.4%
|
| -7 | Does not apply | 1 |
0.2%
|
| 0 | No obstacle | 367 |
73.1%
|
| 1 | Minor obstacle | 76 |
15.1%
|
| 2 | Moderate obstacle | 41 |
8.2%
|
| 3 | Major obstacle | 13 |
2.6%
|
| 4 | Very severe obstacle | 2 |
0.4%
|