| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 1 |
0.1%
|
| -7 | Does not apply | 10 |
1.1%
|
| 0 | No obstacle | 197 |
20.8%
|
| 1 | Minor obstacle | 280 |
29.6%
|
| 2 | Moderate obstacle | 306 |
32.3%
|
| 3 | Major obstacle | 126 |
13.3%
|
| 4 | Very severe obstacle | 27 |
2.9%
|