| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 53 |
0.3%
|
| -7 | Does not apply | 92 |
0.5%
|
| 0 | No obstacle | 5386 |
28.9%
|
| 1 | Minor obstacle | 3642 |
19.5%
|
| 2 | Moderate obstacle | 3892 |
20.9%
|
| 3 | Major obstacle | 3257 |
17.5%
|
| 4 | Very severe obstacle | 2335 |
12.5%
|