| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 2 |
0.2%
|
| -7 | Does not apply | 1 |
0.1%
|
| 0 | No obstacle | 148 |
11.2%
|
| 1 | Minor obstacle | 204 |
15.4%
|
| 2 | Moderate obstacle | 715 |
54.1%
|
| 3 | Major obstacle | 203 |
15.4%
|
| 4 | Very severe obstacle | 49 |
3.7%
|