| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 46 |
0.5%
|
| -7 | Does not apply | 82 |
0.9%
|
| 0 | No obstacle | 4048 |
43.2%
|
| 1 | Minor obstacle | 1875 |
20%
|
| 2 | Moderate obstacle | 1698 |
18.1%
|
| 3 | Major obstacle | 1114 |
11.9%
|
| 4 | Very severe obstacle | 513 |
5.5%
|