| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 1 |
0.1%
|
| -7 | Does not apply | 4 |
0.4%
|
| 0 | No obstacle | 464 |
46.5%
|
| 1 | Minor obstacle | 263 |
26.4%
|
| 2 | Moderate obstacle | 194 |
19.4%
|
| 3 | Major obstacle | 63 |
6.3%
|
| 4 | Very severe obstacle | 9 |
0.9%
|