| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 1 |
0.3%
|
| -7 | Does not apply | 1 |
0.3%
|
| 0 | No obstacle | 35 |
12%
|
| 1 | Minor obstacle | 14 |
4.8%
|
| 2 | Moderate obstacle | 33 |
11.3%
|
| 3 | Major obstacle | 79 |
27.1%
|
| 4 | Very severe obstacle | 129 |
44.2%
|