| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 25 |
0.1%
|
| -7 | Does not apply | 20 |
0.1%
|
| 0 | No obstacle | 5833 |
31.3%
|
| 1 | Minor obstacle | 3961 |
21.2%
|
| 2 | Moderate obstacle | 4304 |
23.1%
|
| 3 | Major obstacle | 3339 |
17.9%
|
| 4 | Very severe obstacle | 1175 |
6.3%
|