| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 6 |
0.6%
|
| -7 | Does not apply | 1 |
0.1%
|
| 0 | No obstacle | 171 |
17.1%
|
| 1 | Minor obstacle | 227 |
22.7%
|
| 2 | Moderate obstacle | 247 |
24.7%
|
| 3 | Major obstacle | 290 |
29%
|
| 4 | Very severe obstacle | 59 |
5.9%
|