| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 0 |
0%
|
| -7 | Does not apply | 7 |
0.3%
|
| 0 | No obstacle | 563 |
27.2%
|
| 1 | Minor obstacle | 238 |
11.5%
|
| 2 | Moderate obstacle | 359 |
17.4%
|
| 3 | Major obstacle | 425 |
20.5%
|
| 4 | Very severe obstacle | 477 |
23.1%
|