| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 16 |
1.6%
|
| -7 | Does not apply | 9 |
0.9%
|
| 0 | No obstacle | 605 |
60%
|
| 1 | Minor obstacle | 242 |
24%
|
| 2 | Moderate obstacle | 117 |
11.6%
|
| 3 | Major obstacle | 16 |
1.6%
|
| 4 | Very severe obstacle | 3 |
0.3%
|