| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 9 |
0.5%
|
| -7 | Does not apply | 427 |
25.7%
|
| 0 | No obstacle | 508 |
30.5%
|
| 1 | Minor obstacle | 225 |
13.5%
|
| 2 | Moderate obstacle | 297 |
17.9%
|
| 3 | Major obstacle | 157 |
9.4%
|
| 4 | Very severe obstacle | 40 |
2.4%
|