| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 8 |
0.1%
|
| -7 | Does not apply | 20 |
0.2%
|
| 0 | No obstacle | 4651 |
49.6%
|
| 1 | Minor obstacle | 2338 |
24.9%
|
| 2 | Moderate obstacle | 1329 |
14.2%
|
| 3 | Major obstacle | 706 |
7.5%
|
| 4 | Very severe obstacle | 324 |
3.5%
|