| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 1 |
0.2%
|
| -7 | Does not apply | 1 |
0.2%
|
| 0 | No obstacle | 410 |
68.3%
|
| 1 | Minor obstacle | 74 |
12.3%
|
| 2 | Moderate obstacle | 66 |
11%
|
| 3 | Major obstacle | 35 |
5.8%
|
| 4 | Very severe obstacle | 13 |
2.2%
|