| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 0 |
0%
|
| -7 | Does not apply | 4 |
0.5%
|
| 0 | No obstacle | 244 |
32.1%
|
| 1 | Minor obstacle | 155 |
20.4%
|
| 2 | Moderate obstacle | 209 |
27.5%
|
| 3 | Major obstacle | 117 |
15.4%
|
| 4 | Very severe obstacle | 31 |
4.1%
|