| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 3 |
0.8%
|
| -7 | Does not apply | 4 |
1.1%
|
| 0 | No obstacle | 249 |
69.6%
|
| 1 | Minor obstacle | 55 |
15.4%
|
| 2 | Moderate obstacle | 31 |
8.7%
|
| 3 | Major obstacle | 12 |
3.4%
|
| 4 | Very severe obstacle | 4 |
1.1%
|