| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 1 |
0.7%
|
| -7 | Does not apply | 1 |
0.7%
|
| 0 | No obstacle | 51 |
34%
|
| 1 | Minor obstacle | 33 |
22%
|
| 2 | Moderate obstacle | 15 |
10%
|
| 3 | Major obstacle | 25 |
16.7%
|
| 4 | Very severe obstacle | 24 |
16%
|