| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 0 |
0%
|
| -7 | Does not apply | 22 |
3.5%
|
| 0 | No obstacle | 424 |
68.1%
|
| 1 | Minor obstacle | 112 |
18%
|
| 2 | Moderate obstacle | 50 |
8%
|
| 3 | Major obstacle | 13 |
2.1%
|
| 4 | Very severe obstacle | 2 |
0.3%
|