| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 12 |
0.1%
|
| -7 | Does not apply | 109 |
0.6%
|
| 0 | No obstacle | 7838 |
42%
|
| 1 | Minor obstacle | 5273 |
28.3%
|
| 2 | Moderate obstacle | 3397 |
18.2%
|
| 3 | Major obstacle | 1494 |
8%
|
| 4 | Very severe obstacle | 534 |
2.9%
|