| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 2 |
0.2%
|
| -7 | Does not apply | 9 |
0.9%
|
| 0 | No obstacle | 155 |
16%
|
| 1 | Minor obstacle | 163 |
16.9%
|
| 2 | Moderate obstacle | 301 |
31.2%
|
| 3 | Major obstacle | 251 |
26%
|
| 4 | Very severe obstacle | 85 |
8.8%
|