| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 13 |
1%
|
| -7 | Does not apply | 6 |
0.4%
|
| 0 | No obstacle | 123 |
9.2%
|
| 1 | Minor obstacle | 135 |
10.1%
|
| 2 | Moderate obstacle | 359 |
26.9%
|
| 3 | Major obstacle | 423 |
31.6%
|
| 4 | Very severe obstacle | 278 |
20.8%
|