| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 0 | |
| -7 | Does not apply | 1 |
0.3%
|
| 0 | No obstacle | 166 |
46.1%
|
| 1 | Minor obstacle | 116 |
32.2%
|
| 2 | Moderate obstacle | 58 |
16.1%
|
| 3 | Major obstacle | 13 |
3.6%
|
| 4 | Very severe obstacle | 6 |
1.7%
|