| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 2 |
0.6%
|
| -7 | Does not apply | 6 |
1.7%
|
| 0 | No obstacle | 241 |
66.9%
|
| 1 | Minor obstacle | 45 |
12.5%
|
| 2 | Moderate obstacle | 37 |
10.3%
|
| 3 | Major obstacle | 13 |
3.6%
|
| 4 | Very severe obstacle | 16 |
4.4%
|