| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 2 |
0.5%
|
| -7 | Does not apply | 4 |
1.1%
|
| 0 | No obstacle | 291 |
79.1%
|
| 1 | Minor obstacle | 28 |
7.6%
|
| 2 | Moderate obstacle | 29 |
7.9%
|
| 3 | Major obstacle | 9 |
2.4%
|
| 4 | Very severe obstacle | 5 |
1.4%
|