| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 1 |
0.1%
|
| -7 | Does not apply | 1 |
0.1%
|
| 0 | No obstacle | 657 |
79.1%
|
| 1 | Minor obstacle | 85 |
10.2%
|
| 2 | Moderate obstacle | 24 |
2.9%
|
| 3 | Major obstacle | 25 |
3%
|
| 4 | Very severe obstacle | 38 |
4.6%
|