| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 2 |
0.3%
|
| -7 | Does not apply | 3 |
0.5%
|
| 0 | No obstacle | 128 |
19.7%
|
| 1 | Minor obstacle | 125 |
19.3%
|
| 2 | Moderate obstacle | 171 |
26.3%
|
| 3 | Major obstacle | 103 |
15.9%
|
| 4 | Very severe obstacle | 117 |
18%
|