| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 1 |
0.1%
|
| -7 | Does not apply | 1 |
0.1%
|
| 0 | No obstacle | 371 |
37.1%
|
| 1 | Minor obstacle | 399 |
39.9%
|
| 2 | Moderate obstacle | 129 |
12.9%
|
| 3 | Major obstacle | 88 |
8.8%
|
| 4 | Very severe obstacle | 12 |
1.2%
|