| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 11 |
0.9%
|
| -7 | Does not apply | 11 |
0.9%
|
| 0 | No obstacle | 525 |
43.2%
|
| 1 | Minor obstacle | 330 |
27.1%
|
| 2 | Moderate obstacle | 275 |
22.6%
|
| 3 | Major obstacle | 50 |
4.1%
|
| 4 | Very severe obstacle | 14 |
1.2%
|