| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 24 |
1.1%
|
| -7 | Does not apply | 1009 |
46.1%
|
| 0 | No obstacle | 1103 |
50.4%
|
| 1 | Minor obstacle | 32 |
1.5%
|
| 2 | Moderate obstacle | 10 |
0.5%
|
| 3 | Major obstacle | 9 |
0.4%
|
| 4 | Very severe obstacle | 2 |
0.1%
|