| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 1 |
0.1%
|
| -7 | Does not apply | 10 |
1%
|
| 0 | No obstacle | 202 |
20.9%
|
| 1 | Minor obstacle | 284 |
29.4%
|
| 2 | Moderate obstacle | 311 |
32.2%
|
| 3 | Major obstacle | 130 |
13.5%
|
| 4 | Very severe obstacle | 28 |
2.9%
|