| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 2 |
0.1%
|
| -7 | Does not apply | 256 |
16.9%
|
| 0 | No obstacle | 768 |
50.6%
|
| 1 | Minor obstacle | 158 |
10.4%
|
| 2 | Moderate obstacle | 243 |
16%
|
| 3 | Major obstacle | 58 |
3.8%
|
| 4 | Very severe obstacle | 33 |
2.2%
|