| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 4 |
0.3%
|
| -7 | Does not apply | 3 |
0.2%
|
| 0 | No obstacle | 434 |
33.4%
|
| 1 | Minor obstacle | 371 |
28.5%
|
| 2 | Moderate obstacle | 339 |
26.1%
|
| 3 | Major obstacle | 115 |
8.8%
|
| 4 | Very severe obstacle | 34 |
2.6%
|