| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 4 |
0.6%
|
| -7 | Does not apply | 5 |
0.7%
|
| 0 | No obstacle | 450 |
62.2%
|
| 1 | Minor obstacle | 103 |
14.2%
|
| 2 | Moderate obstacle | 120 |
16.6%
|
| 3 | Major obstacle | 33 |
4.6%
|
| 4 | Very severe obstacle | 8 |
1.1%
|