| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 1 |
0.1%
|
| -7 | Does not apply | 0 |
0%
|
| 0 | No obstacle | 118 |
8.9%
|
| 1 | Minor obstacle | 176 |
13.3%
|
| 2 | Moderate obstacle | 741 |
56.1%
|
| 3 | Major obstacle | 245 |
18.5%
|
| 4 | Very severe obstacle | 41 |
3.1%
|