| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 1 |
0.1%
|
| -7 | Does not apply | 1 |
0.1%
|
| 0 | No obstacle | 85 |
8.3%
|
| 1 | Minor obstacle | 112 |
11%
|
| 2 | Moderate obstacle | 185 |
18.2%
|
| 3 | Major obstacle | 183 |
18%
|
| 4 | Very severe obstacle | 452 |
44.4%
|