| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 15 |
1%
|
| -7 | Does not apply | 85 |
5.9%
|
| 0 | No obstacle | 944 |
65.3%
|
| 1 | Minor obstacle | 199 |
13.8%
|
| 2 | Moderate obstacle | 139 |
9.6%
|
| 3 | Major obstacle | 45 |
3.1%
|
| 4 | Very severe obstacle | 19 |
1.3%
|