| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 1 |
0.1%
|
| -7 | Does not apply | 0 |
0%
|
| 0 | No obstacle | 109 |
8.2%
|
| 1 | Minor obstacle | 182 |
13.8%
|
| 2 | Moderate obstacle | 747 |
56.5%
|
| 3 | Major obstacle | 223 |
16.9%
|
| 4 | Very severe obstacle | 60 |
4.5%
|