| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 5 |
0.5%
|
| -7 | Does not apply | 4 |
0.4%
|
| 0 | No obstacle | 439 |
40.4%
|
| 1 | Minor obstacle | 178 |
16.4%
|
| 2 | Moderate obstacle | 253 |
23.3%
|
| 3 | Major obstacle | 128 |
11.8%
|
| 4 | Very severe obstacle | 79 |
7.3%
|