| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 4 |
0.4%
|
| -7 | Does not apply | 2 |
0.2%
|
| 0 | No obstacle | 467 |
45.4%
|
| 1 | Minor obstacle | 173 |
16.8%
|
| 2 | Moderate obstacle | 110 |
10.7%
|
| 3 | Major obstacle | 208 |
20.2%
|
| 4 | Very severe obstacle | 64 |
6.2%
|