| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 8 |
0.6%
|
| -7 | Does not apply | 2 |
0.1%
|
| 0 | No obstacle | 897 |
63.3%
|
| 1 | Minor obstacle | 172 |
12.1%
|
| 2 | Moderate obstacle | 149 |
10.5%
|
| 3 | Major obstacle | 112 |
7.9%
|
| 4 | Very severe obstacle | 76 |
5.4%
|