| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 5 |
0.5%
|
| -7 | Does not apply | 2 |
0.2%
|
| 0 | No obstacle | 621 |
62.2%
|
| 1 | Minor obstacle | 146 |
14.6%
|
| 2 | Moderate obstacle | 113 |
11.3%
|
| 3 | Major obstacle | 99 |
9.9%
|
| 4 | Very severe obstacle | 12 |
1.2%
|