| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 24 |
1.9%
|
| -7 | Does not apply | 9 |
0.7%
|
| 0 | No obstacle | 1043 |
84.2%
|
| 1 | Minor obstacle | 95 |
7.7%
|
| 2 | Moderate obstacle | 42 |
3.4%
|
| 3 | Major obstacle | 19 |
1.5%
|
| 4 | Very severe obstacle | 7 |
0.6%
|