| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 33 |
0.2%
|
| -7 | Does not apply | 59 |
0.3%
|
| 0 | No obstacle | 8335 |
44.7%
|
| 1 | Minor obstacle | 4807 |
25.8%
|
| 2 | Moderate obstacle | 3120 |
16.7%
|
| 3 | Major obstacle | 1623 |
8.7%
|
| 4 | Very severe obstacle | 680 |
3.6%
|