| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 1 |
0%
|
| -7 | Does not apply | 4 |
0.2%
|
| 0 | No obstacle | 531 |
20.2%
|
| 1 | Minor obstacle | 524 |
19.9%
|
| 2 | Moderate obstacle | 1034 |
39.2%
|
| 3 | Major obstacle | 414 |
15.7%
|
| 4 | Very severe obstacle | 127 |
4.8%
|