| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 1 |
0.3%
|
| -7 | Does not apply | 2 |
0.6%
|
| 0 | No obstacle | 22 |
6.1%
|
| 1 | Minor obstacle | 83 |
23.1%
|
| 2 | Moderate obstacle | 113 |
31.4%
|
| 3 | Major obstacle | 95 |
26.4%
|
| 4 | Very severe obstacle | 44 |
12.2%
|