| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 27 |
2.2%
|
| -7 | Does not apply | 8 |
0.6%
|
| 0 | No obstacle | 770 |
62.1%
|
| 1 | Minor obstacle | 153 |
12.3%
|
| 2 | Moderate obstacle | 177 |
14.3%
|
| 3 | Major obstacle | 58 |
4.7%
|
| 4 | Very severe obstacle | 46 |
3.7%
|