| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 7 |
0.5%
|
| -7 | Does not apply | 4 |
0.3%
|
| 0 | No obstacle | 412 |
30.8%
|
| 1 | Minor obstacle | 212 |
15.9%
|
| 2 | Moderate obstacle | 211 |
15.8%
|
| 3 | Major obstacle | 269 |
20.1%
|
| 4 | Very severe obstacle | 222 |
16.6%
|