| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 1 |
0.1%
|
| -7 | Does not apply | 115 |
11.2%
|
| 0 | No obstacle | 685 |
66.9%
|
| 1 | Minor obstacle | 142 |
13.9%
|
| 2 | Moderate obstacle | 51 |
5%
|
| 3 | Major obstacle | 20 |
2%
|
| 4 | Very severe obstacle | 10 |
1%
|