| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 3 |
0.3%
|
| -7 | Does not apply | 18 |
1.9%
|
| 0 | No obstacle | 629 |
65.9%
|
| 1 | Minor obstacle | 142 |
14.9%
|
| 2 | Moderate obstacle | 110 |
11.5%
|
| 3 | Major obstacle | 36 |
3.8%
|
| 4 | Very severe obstacle | 17 |
1.8%
|