| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 5 |
0.5%
|
| -7 | Does not apply | 19 |
1.9%
|
| 0 | No obstacle | 156 |
15.3%
|
| 1 | Minor obstacle | 96 |
9.4%
|
| 2 | Moderate obstacle | 140 |
13.7%
|
| 3 | Major obstacle | 219 |
21.5%
|
| 4 | Very severe obstacle | 384 |
37.7%
|