| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 7 |
0.7%
|
| -7 | Does not apply | 7 |
0.7%
|
| 0 | No obstacle | 321 |
32.5%
|
| 1 | Minor obstacle | 139 |
14.1%
|
| 2 | Moderate obstacle | 248 |
25.1%
|
| 3 | Major obstacle | 186 |
18.8%
|
| 4 | Very severe obstacle | 79 |
8%
|