| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 3 |
0.1%
|
| -7 | Does not apply | 0 |
0%
|
| 0 | No obstacle | 1015 |
38.5%
|
| 1 | Minor obstacle | 528 |
20%
|
| 2 | Moderate obstacle | 405 |
15.4%
|
| 3 | Major obstacle | 345 |
13.1%
|
| 4 | Very severe obstacle | 339 |
12.9%
|