| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 12 |
0.5%
|
| -7 | Does not apply | 28 |
1.3%
|
| 0 | No obstacle | 1844 |
84.2%
|
| 1 | Minor obstacle | 209 |
9.5%
|
| 2 | Moderate obstacle | 63 |
2.9%
|
| 3 | Major obstacle | 28 |
1.3%
|
| 4 | Very severe obstacle | 5 |
0.2%
|