| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 2 |
0.1%
|
| -7 | Does not apply | 0 |
0%
|
| 0 | No obstacle | 1100 |
40.8%
|
| 1 | Minor obstacle | 841 |
31.2%
|
| 2 | Moderate obstacle | 528 |
19.6%
|
| 3 | Major obstacle | 185 |
6.9%
|
| 4 | Very severe obstacle | 41 |
1.5%
|