| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 4 |
0.3%
|
| -7 | Does not apply | 131 |
8.6%
|
| 0 | No obstacle | 762 |
50.2%
|
| 1 | Minor obstacle | 184 |
12.1%
|
| 2 | Moderate obstacle | 367 |
24.2%
|
| 3 | Major obstacle | 53 |
3.5%
|
| 4 | Very severe obstacle | 17 |
1.1%
|