| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 34 |
0.1%
|
| -7 | Does not apply | 144 |
0.5%
|
| 0 | No obstacle | 12834 |
44%
|
| 1 | Minor obstacle | 8268 |
28.4%
|
| 2 | Moderate obstacle | 4300 |
14.8%
|
| 3 | Major obstacle | 2337 |
8%
|
| 4 | Very severe obstacle | 1219 |
4.2%
|