| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 2 |
0.6%
|
| -7 | Does not apply | 1 |
0.3%
|
| 0 | No obstacle | 77 |
24.1%
|
| 1 | Minor obstacle | 55 |
17.2%
|
| 2 | Moderate obstacle | 89 |
27.8%
|
| 3 | Major obstacle | 67 |
20.9%
|
| 4 | Very severe obstacle | 29 |
9.1%
|