| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 12 |
0.1%
|
| -7 | Does not apply | 125 |
1.3%
|
| 0 | No obstacle | 4186 |
44.6%
|
| 1 | Minor obstacle | 2162 |
23.1%
|
| 2 | Moderate obstacle | 1606 |
17.1%
|
| 3 | Major obstacle | 1048 |
11.2%
|
| 4 | Very severe obstacle | 237 |
2.5%
|