| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 1 |
0.1%
|
| -7 | Does not apply | 0 |
0%
|
| 0 | No obstacle | 820 |
57.3%
|
| 1 | Minor obstacle | 291 |
20.3%
|
| 2 | Moderate obstacle | 191 |
13.3%
|
| 3 | Major obstacle | 100 |
7%
|
| 4 | Very severe obstacle | 29 |
2%
|