| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 3 |
0.6%
|
| -7 | Does not apply | 26 |
5.2%
|
| 0 | No obstacle | 334 |
66.5%
|
| 1 | Minor obstacle | 62 |
12.4%
|
| 2 | Moderate obstacle | 48 |
9.6%
|
| 3 | Major obstacle | 23 |
4.6%
|
| 4 | Very severe obstacle | 6 |
1.2%
|