| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 6 |
0.4%
|
| -7 | Does not apply | 20 |
1.5%
|
| 0 | No obstacle | 461 |
34.5%
|
| 1 | Minor obstacle | 244 |
18.2%
|
| 2 | Moderate obstacle | 232 |
17.4%
|
| 3 | Major obstacle | 236 |
17.7%
|
| 4 | Very severe obstacle | 138 |
10.3%
|