| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 1 |
0.1%
|
| -7 | Does not apply | 5 |
0.6%
|
| 0 | No obstacle | 630 |
74.1%
|
| 1 | Minor obstacle | 123 |
14.5%
|
| 2 | Moderate obstacle | 54 |
6.4%
|
| 3 | Major obstacle | 20 |
2.4%
|
| 4 | Very severe obstacle | 17 |
2%
|