| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 1 |
0.3%
|
| -7 | Does not apply | 3 |
0.8%
|
| 0 | No obstacle | 231 |
63.5%
|
| 1 | Minor obstacle | 40 |
11%
|
| 2 | Moderate obstacle | 33 |
9.1%
|
| 3 | Major obstacle | 23 |
6.3%
|
| 4 | Very severe obstacle | 33 |
9.1%
|