| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 1 |
0.1%
|
| -7 | Does not apply | 2 |
0.2%
|
| 0 | No obstacle | 270 |
27.4%
|
| 1 | Minor obstacle | 203 |
20.6%
|
| 2 | Moderate obstacle | 158 |
16%
|
| 3 | Major obstacle | 126 |
12.8%
|
| 4 | Very severe obstacle | 227 |
23%
|