| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 19 |
1%
|
| -7 | Does not apply | 15 |
0.8%
|
| 0 | No obstacle | 1322 |
66.3%
|
| 1 | Minor obstacle | 187 |
9.4%
|
| 2 | Moderate obstacle | 234 |
11.7%
|
| 3 | Major obstacle | 154 |
7.7%
|
| 4 | Very severe obstacle | 64 |
3.2%
|