| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 1 |
0.1%
|
| -7 | Does not apply | 3 |
0.3%
|
| 0 | No obstacle | 548 |
53.3%
|
| 1 | Minor obstacle | 228 |
22.2%
|
| 2 | Moderate obstacle | 148 |
14.4%
|
| 3 | Major obstacle | 82 |
8%
|
| 4 | Very severe obstacle | 18 |
1.8%
|