| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 3 |
0.4%
|
| -7 | Does not apply | 22 |
2.6%
|
| 0 | No obstacle | 616 |
74.1%
|
| 1 | Minor obstacle | 107 |
12.9%
|
| 2 | Moderate obstacle | 31 |
3.7%
|
| 3 | Major obstacle | 31 |
3.7%
|
| 4 | Very severe obstacle | 21 |
2.5%
|