| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 20 |
0.2%
|
| -7 | Does not apply | 35 |
0.4%
|
| 0 | No obstacle | 5560 |
59.3%
|
| 1 | Minor obstacle | 1494 |
15.9%
|
| 2 | Moderate obstacle | 1322 |
14.1%
|
| 3 | Major obstacle | 749 |
8%
|
| 4 | Very severe obstacle | 196 |
2.1%
|