| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 6 |
0.6%
|
| -7 | Does not apply | 23 |
2.3%
|
| 0 | No obstacle | 363 |
36.2%
|
| 1 | Minor obstacle | 276 |
27.5%
|
| 2 | Moderate obstacle | 193 |
19.3%
|
| 3 | Major obstacle | 102 |
10.2%
|
| 4 | Very severe obstacle | 39 |
3.9%
|