| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 1 |
0.1%
|
| -7 | Does not apply | 22 |
2.2%
|
| 0 | No obstacle | 547 |
54.3%
|
| 1 | Minor obstacle | 185 |
18.4%
|
| 2 | Moderate obstacle | 140 |
13.9%
|
| 3 | Major obstacle | 73 |
7.2%
|
| 4 | Very severe obstacle | 39 |
3.9%
|