| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 7 |
0.5%
|
| -7 | Does not apply | 13 |
1%
|
| 0 | No obstacle | 262 |
19.6%
|
| 1 | Minor obstacle | 204 |
15.3%
|
| 2 | Moderate obstacle | 321 |
24%
|
| 3 | Major obstacle | 288 |
21.5%
|
| 4 | Very severe obstacle | 242 |
18.1%
|