| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 2 |
0.2%
|
| -7 | Does not apply | 9 |
1%
|
| 0 | No obstacle | 151 |
15.9%
|
| 1 | Minor obstacle | 158 |
16.7%
|
| 2 | Moderate obstacle | 296 |
31.3%
|
| 3 | Major obstacle | 246 |
26%
|
| 4 | Very severe obstacle | 85 |
9%
|