| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 2 |
0.1%
|
| -7 | Does not apply | 23 |
1.5%
|
| 0 | No obstacle | 746 |
49.1%
|
| 1 | Minor obstacle | 189 |
12.5%
|
| 2 | Moderate obstacle | 465 |
30.6%
|
| 3 | Major obstacle | 71 |
4.7%
|
| 4 | Very severe obstacle | 22 |
1.4%
|