| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 3 |
0.3%
|
| -7 | Does not apply | 13 |
1.3%
|
| 0 | No obstacle | 624 |
62.3%
|
| 1 | Minor obstacle | 216 |
21.6%
|
| 2 | Moderate obstacle | 59 |
5.9%
|
| 3 | Major obstacle | 59 |
5.9%
|
| 4 | Very severe obstacle | 28 |
2.8%
|