| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 1 |
0.1%
|
| -7 | Does not apply | 30 |
2.9%
|
| 0 | No obstacle | 810 |
79.1%
|
| 1 | Minor obstacle | 126 |
12.3%
|
| 2 | Moderate obstacle | 33 |
3.2%
|
| 3 | Major obstacle | 16 |
1.6%
|
| 4 | Very severe obstacle | 8 |
0.8%
|