| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 3 |
0.2%
|
| -7 | Does not apply | 19 |
1.2%
|
| 0 | No obstacle | 1244 |
79.1%
|
| 1 | Minor obstacle | 212 |
13.5%
|
| 2 | Moderate obstacle | 70 |
4.5%
|
| 3 | Major obstacle | 17 |
1.1%
|
| 4 | Very severe obstacle | 8 |
0.5%
|