| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 1 |
0.3%
|
| -7 | Does not apply | 2 |
0.6%
|
| 0 | No obstacle | 285 |
79.6%
|
| 1 | Minor obstacle | 16 |
4.5%
|
| 2 | Moderate obstacle | 20 |
5.6%
|
| 3 | Major obstacle | 19 |
5.3%
|
| 4 | Very severe obstacle | 15 |
4.2%
|