| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 1 |
0.1%
|
| -7 | Does not apply | 3 |
0.3%
|
| 0 | No obstacle | 635 |
62%
|
| 1 | Minor obstacle | 225 |
22%
|
| 2 | Moderate obstacle | 96 |
9.4%
|
| 3 | Major obstacle | 53 |
5.2%
|
| 4 | Very severe obstacle | 11 |
1.1%
|