| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 4 |
0.3%
|
| -7 | Does not apply | 1 |
0.1%
|
| 0 | No obstacle | 808 |
57.1%
|
| 1 | Minor obstacle | 249 |
17.6%
|
| 2 | Moderate obstacle | 151 |
10.7%
|
| 3 | Major obstacle | 128 |
9%
|
| 4 | Very severe obstacle | 75 |
5.3%
|