| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 5 |
0.4%
|
| -7 | Does not apply | 1 |
0.1%
|
| 0 | No obstacle | 865 |
61.1%
|
| 1 | Minor obstacle | 227 |
16%
|
| 2 | Moderate obstacle | 172 |
12.1%
|
| 3 | Major obstacle | 85 |
6%
|
| 4 | Very severe obstacle | 61 |
4.3%
|