| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 1 |
0.2%
|
| -7 | Does not apply | 3 |
0.6%
|
| 0 | No obstacle | 112 |
21.9%
|
| 1 | Minor obstacle | 211 |
41.3%
|
| 2 | Moderate obstacle | 118 |
23.1%
|
| 3 | Major obstacle | 63 |
12.3%
|
| 4 | Very severe obstacle | 3 |
0.6%
|