| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 12 |
0.1%
|
| -7 | Does not apply | 32 |
0.3%
|
| 0 | No obstacle | 3649 |
38.9%
|
| 1 | Minor obstacle | 2363 |
25.2%
|
| 2 | Moderate obstacle | 2099 |
22.4%
|
| 3 | Major obstacle | 1023 |
10.9%
|
| 4 | Very severe obstacle | 198 |
2.1%
|