| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 2 |
0.1%
|
| -7 | Does not apply | 2 |
0.1%
|
| 0 | No obstacle | 1216 |
45.1%
|
| 1 | Minor obstacle | 779 |
28.9%
|
| 2 | Moderate obstacle | 470 |
17.4%
|
| 3 | Major obstacle | 177 |
6.6%
|
| 4 | Very severe obstacle | 51 |
1.9%
|