| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 24 |
0.9%
|
| -7 | Does not apply | 4 |
0.1%
|
| 0 | No obstacle | 1183 |
43.9%
|
| 1 | Minor obstacle | 814 |
30.2%
|
| 2 | Moderate obstacle | 522 |
19.4%
|
| 3 | Major obstacle | 127 |
4.7%
|
| 4 | Very severe obstacle | 23 |
0.9%
|