| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 2 |
0.1%
|
| -7 | Does not apply | 377 |
24.8%
|
| 0 | No obstacle | 746 |
49.1%
|
| 1 | Minor obstacle | 119 |
7.8%
|
| 2 | Moderate obstacle | 230 |
15.2%
|
| 3 | Major obstacle | 36 |
2.4%
|
| 4 | Very severe obstacle | 8 |
0.5%
|