| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 3 |
0.2%
|
| -7 | Does not apply | 3 |
0.2%
|
| 0 | No obstacle | 926 |
65.4%
|
| 1 | Minor obstacle | 223 |
15.7%
|
| 2 | Moderate obstacle | 137 |
9.7%
|
| 3 | Major obstacle | 83 |
5.9%
|
| 4 | Very severe obstacle | 41 |
2.9%
|