| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 2 |
0.2%
|
| -7 | Does not apply | 12 |
1.2%
|
| 0 | No obstacle | 251 |
24.5%
|
| 1 | Minor obstacle | 176 |
17.2%
|
| 2 | Moderate obstacle | 204 |
19.9%
|
| 3 | Major obstacle | 234 |
22.8%
|
| 4 | Very severe obstacle | 146 |
14.2%
|