| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 2 |
0.5%
|
| -7 | Does not apply | 35 |
8.7%
|
| 0 | No obstacle | 210 |
52.2%
|
| 1 | Minor obstacle | 65 |
16.2%
|
| 2 | Moderate obstacle | 30 |
7.5%
|
| 3 | Major obstacle | 29 |
7.2%
|
| 4 | Very severe obstacle | 31 |
7.7%
|