| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 2 |
0.3%
|
| -7 | Does not apply | 6 |
1%
|
| 0 | No obstacle | 381 |
63.5%
|
| 1 | Minor obstacle | 142 |
23.7%
|
| 2 | Moderate obstacle | 51 |
8.5%
|
| 3 | Major obstacle | 13 |
2.2%
|
| 4 | Very severe obstacle | 5 |
0.8%
|