| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 1 |
0.1%
|
| -7 | Does not apply | 2 |
0.2%
|
| 0 | No obstacle | 293 |
24.1%
|
| 1 | Minor obstacle | 178 |
14.6%
|
| 2 | Moderate obstacle | 476 |
39.1%
|
| 3 | Major obstacle | 235 |
19.3%
|
| 4 | Very severe obstacle | 31 |
2.5%
|