| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 1 |
0.1%
|
| -7 | Does not apply | 9 |
0.9%
|
| 0 | No obstacle | 402 |
39.9%
|
| 1 | Minor obstacle | 215 |
21.4%
|
| 2 | Moderate obstacle | 158 |
15.7%
|
| 3 | Major obstacle | 123 |
12.2%
|
| 4 | Very severe obstacle | 99 |
9.8%
|