| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 17 |
0.2%
|
| -7 | Does not apply | 11 |
0.1%
|
| 0 | No obstacle | 4014 |
42.8%
|
| 1 | Minor obstacle | 1658 |
17.7%
|
| 2 | Moderate obstacle | 1907 |
20.3%
|
| 3 | Major obstacle | 1290 |
13.8%
|
| 4 | Very severe obstacle | 479 |
5.1%
|