| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 20 |
0.2%
|
| -7 | Does not apply | 13 |
0.1%
|
| 0 | No obstacle | 4173 |
44.5%
|
| 1 | Minor obstacle | 1629 |
17.4%
|
| 2 | Moderate obstacle | 1679 |
17.9%
|
| 3 | Major obstacle | 1495 |
15.9%
|
| 4 | Very severe obstacle | 367 |
3.9%
|