| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 4 |
0.3%
|
| -7 | Does not apply | 5 |
0.4%
|
| 0 | No obstacle | 429 |
35.3%
|
| 1 | Minor obstacle | 387 |
31.8%
|
| 2 | Moderate obstacle | 273 |
22.5%
|
| 3 | Major obstacle | 94 |
7.7%
|
| 4 | Very severe obstacle | 24 |
2%
|