| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 8 |
0.4%
|
| -7 | Does not apply | 44 |
2.1%
|
| 0 | No obstacle | 598 |
28.9%
|
| 1 | Minor obstacle | 506 |
24.5%
|
| 2 | Moderate obstacle | 508 |
24.6%
|
| 3 | Major obstacle | 275 |
13.3%
|
| 4 | Very severe obstacle | 130 |
6.3%
|