| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 9 |
0.3%
|
| -7 | Does not apply | 43 |
1.6%
|
| 0 | No obstacle | 1836 |
68.1%
|
| 1 | Minor obstacle | 422 |
15.6%
|
| 2 | Moderate obstacle | 278 |
10.3%
|
| 3 | Major obstacle | 85 |
3.2%
|
| 4 | Very severe obstacle | 24 |
0.9%
|