| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 46 |
0.2%
|
| -7 | Does not apply | 211 |
0.7%
|
| 0 | No obstacle | 10277 |
35.3%
|
| 1 | Minor obstacle | 8837 |
30.3%
|
| 2 | Moderate obstacle | 6011 |
20.6%
|
| 3 | Major obstacle | 2985 |
10.2%
|
| 4 | Very severe obstacle | 769 |
2.6%
|