| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 9 |
0.5%
|
| -7 | Does not apply | 73 |
4.4%
|
| 0 | No obstacle | 432 |
26%
|
| 1 | Minor obstacle | 244 |
14.7%
|
| 2 | Moderate obstacle | 394 |
23.7%
|
| 3 | Major obstacle | 376 |
22.6%
|
| 4 | Very severe obstacle | 135 |
8.1%
|