| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 0 |
0%
|
| -7 | Does not apply | 24 |
6.5%
|
| 0 | No obstacle | 320 |
87%
|
| 1 | Minor obstacle | 9 |
2.4%
|
| 2 | Moderate obstacle | 6 |
1.6%
|
| 3 | Major obstacle | 7 |
1.9%
|
| 4 | Very severe obstacle | 2 |
0.5%
|