| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 1 |
0.1%
|
| -7 | Does not apply | 4 |
0.3%
|
| 0 | No obstacle | 162 |
13.5%
|
| 1 | Minor obstacle | 161 |
13.4%
|
| 2 | Moderate obstacle | 179 |
14.9%
|
| 3 | Major obstacle | 345 |
28.8%
|
| 4 | Very severe obstacle | 348 |
29%
|