| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 8 |
0.3%
|
| -7 | Does not apply | 1 |
0%
|
| 0 | No obstacle | 1546 |
57.3%
|
| 1 | Minor obstacle | 739 |
27.4%
|
| 2 | Moderate obstacle | 285 |
10.6%
|
| 3 | Major obstacle | 89 |
3.3%
|
| 4 | Very severe obstacle | 29 |
1.1%
|