| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 2 |
0.3%
|
| -7 | Does not apply | 12 |
1.7%
|
| 0 | No obstacle | 411 |
57.9%
|
| 1 | Minor obstacle | 109 |
15.4%
|
| 2 | Moderate obstacle | 103 |
14.5%
|
| 3 | Major obstacle | 52 |
7.3%
|
| 4 | Very severe obstacle | 21 |
3%
|