| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 1 |
0.1%
|
| -7 | Does not apply | 1 |
0.1%
|
| 0 | No obstacle | 259 |
35.5%
|
| 1 | Minor obstacle | 135 |
18.5%
|
| 2 | Moderate obstacle | 148 |
20.3%
|
| 3 | Major obstacle | 95 |
13%
|
| 4 | Very severe obstacle | 90 |
12.3%
|