| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 1 |
0.1%
|
| -7 | Does not apply | 0 |
0%
|
| 0 | No obstacle | 238 |
25.9%
|
| 1 | Minor obstacle | 341 |
37.1%
|
| 2 | Moderate obstacle | 260 |
28.3%
|
| 3 | Major obstacle | 59 |
6.4%
|
| 4 | Very severe obstacle | 20 |
2.2%
|