| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 14 |
0.6%
|
| -7 | Does not apply | 22 |
1%
|
| 0 | No obstacle | 1932 |
88.3%
|
| 1 | Minor obstacle | 145 |
6.6%
|
| 2 | Moderate obstacle | 51 |
2.3%
|
| 3 | Major obstacle | 20 |
0.9%
|
| 4 | Very severe obstacle | 5 |
0.2%
|