| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 12 |
0.1%
|
| -7 | Does not apply | 35 |
0.4%
|
| 0 | No obstacle | 4913 |
52.4%
|
| 1 | Minor obstacle | 2295 |
24.5%
|
| 2 | Moderate obstacle | 1266 |
13.5%
|
| 3 | Major obstacle | 543 |
5.8%
|
| 4 | Very severe obstacle | 312 |
3.3%
|