| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 17 |
0.8%
|
| -7 | Does not apply | 8 |
0.4%
|
| 0 | No obstacle | 2105 |
96.2%
|
| 1 | Minor obstacle | 48 |
2.2%
|
| 2 | Moderate obstacle | 7 |
0.3%
|
| 3 | Major obstacle | 2 |
0.1%
|
| 4 | Very severe obstacle | 2 |
0.1%
|