| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 18 |
0.2%
|
| -7 | Does not apply | 18 |
0.2%
|
| 0 | No obstacle | 4615 |
49.2%
|
| 1 | Minor obstacle | 1841 |
19.6%
|
| 2 | Moderate obstacle | 1535 |
16.4%
|
| 3 | Major obstacle | 940 |
10%
|
| 4 | Very severe obstacle | 409 |
4.4%
|