| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 1 |
0.3%
|
| -7 | Does not apply | 1 |
0.3%
|
| 0 | No obstacle | 88 |
22.7%
|
| 1 | Minor obstacle | 154 |
39.7%
|
| 2 | Moderate obstacle | 61 |
15.7%
|
| 3 | Major obstacle | 78 |
20.1%
|
| 4 | Very severe obstacle | 5 |
1.3%
|