| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 15 |
1.2%
|
| -7 | Does not apply | 8 |
0.6%
|
| 0 | No obstacle | 276 |
21.2%
|
| 1 | Minor obstacle | 327 |
25.2%
|
| 2 | Moderate obstacle | 285 |
21.9%
|
| 3 | Major obstacle | 206 |
15.8%
|
| 4 | Very severe obstacle | 183 |
14.1%
|