| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 5 |
0.2%
|
| -7 | Does not apply | 4 |
0.1%
|
| 0 | No obstacle | 1274 |
47.2%
|
| 1 | Minor obstacle | 585 |
21.7%
|
| 2 | Moderate obstacle | 503 |
18.7%
|
| 3 | Major obstacle | 226 |
8.4%
|
| 4 | Very severe obstacle | 100 |
3.7%
|