| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 1 |
0.1%
|
| -7 | Does not apply | 3 |
0.4%
|
| 0 | No obstacle | 644 |
77.5%
|
| 1 | Minor obstacle | 124 |
14.9%
|
| 2 | Moderate obstacle | 37 |
4.5%
|
| 3 | Major obstacle | 17 |
2%
|
| 4 | Very severe obstacle | 5 |
0.6%
|