| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 6 |
0.4%
|
| -7 | Does not apply | 1 |
0.1%
|
| 0 | No obstacle | 589 |
41.6%
|
| 1 | Minor obstacle | 289 |
20.4%
|
| 2 | Moderate obstacle | 204 |
14.4%
|
| 3 | Major obstacle | 146 |
10.3%
|
| 4 | Very severe obstacle | 181 |
12.8%
|