| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 0 | |
| -7 | Does not apply | 1 |
0.3%
|
| 0 | No obstacle | 120 |
33.3%
|
| 1 | Minor obstacle | 117 |
32.5%
|
| 2 | Moderate obstacle | 86 |
23.9%
|
| 3 | Major obstacle | 31 |
8.6%
|
| 4 | Very severe obstacle | 5 |
1.4%
|