| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 7 |
0.5%
|
| -7 | Does not apply | 6 |
0.5%
|
| 0 | No obstacle | 585 |
44.2%
|
| 1 | Minor obstacle | 376 |
28.4%
|
| 2 | Moderate obstacle | 280 |
21.2%
|
| 3 | Major obstacle | 59 |
4.5%
|
| 4 | Very severe obstacle | 10 |
0.8%
|