| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 24 |
0.3%
|
| -7 | Does not apply | 41 |
0.4%
|
| 0 | No obstacle | 4422 |
47.2%
|
| 1 | Minor obstacle | 1965 |
21%
|
| 2 | Moderate obstacle | 1268 |
13.5%
|
| 3 | Major obstacle | 1011 |
10.8%
|
| 4 | Very severe obstacle | 645 |
6.9%
|