| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 9 |
0.4%
|
| -7 | Does not apply | 173 |
7.9%
|
| 0 | No obstacle | 1965 |
89.8%
|
| 1 | Minor obstacle | 33 |
1.5%
|
| 2 | Moderate obstacle | 3 |
0.1%
|
| 3 | Major obstacle | 5 |
0.2%
|
| 4 | Very severe obstacle | 1 |
0%
|