| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 7 |
0.5%
|
| -7 | Does not apply | 23 |
1.6%
|
| 0 | No obstacle | 420 |
29%
|
| 1 | Minor obstacle | 246 |
17%
|
| 2 | Moderate obstacle | 268 |
18.5%
|
| 3 | Major obstacle | 231 |
16%
|
| 4 | Very severe obstacle | 251 |
17.4%
|