| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 5 |
0.5%
|
| -7 | Does not apply | 630 |
63.1%
|
| 0 | No obstacle | 280 |
28.1%
|
| 1 | Minor obstacle | 50 |
5%
|
| 2 | Moderate obstacle | 28 |
2.8%
|
| 3 | Major obstacle | 4 |
0.4%
|
| 4 | Very severe obstacle | 1 |
0.1%
|