| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 13 |
0.7%
|
| -7 | Does not apply | 4 |
0.2%
|
| 0 | No obstacle | 1007 |
50.5%
|
| 1 | Minor obstacle | 269 |
13.5%
|
| 2 | Moderate obstacle | 286 |
14.3%
|
| 3 | Major obstacle | 203 |
10.2%
|
| 4 | Very severe obstacle | 213 |
10.7%
|