| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 7 |
0.5%
|
| -7 | Does not apply | 9 |
0.7%
|
| 0 | No obstacle | 498 |
37.2%
|
| 1 | Minor obstacle | 230 |
17.2%
|
| 2 | Moderate obstacle | 295 |
22.1%
|
| 3 | Major obstacle | 230 |
17.2%
|
| 4 | Very severe obstacle | 68 |
5.1%
|