| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 1 |
0.1%
|
| -7 | Does not apply | 9 |
1.3%
|
| 0 | No obstacle | 416 |
58.6%
|
| 1 | Minor obstacle | 112 |
15.8%
|
| 2 | Moderate obstacle | 113 |
15.9%
|
| 3 | Major obstacle | 48 |
6.8%
|
| 4 | Very severe obstacle | 11 |
1.5%
|