| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 11 |
0.1%
|
| -7 | Does not apply | 86 |
0.9%
|
| 0 | No obstacle | 4515 |
48.2%
|
| 1 | Minor obstacle | 2146 |
22.9%
|
| 2 | Moderate obstacle | 1429 |
15.2%
|
| 3 | Major obstacle | 910 |
9.7%
|
| 4 | Very severe obstacle | 279 |
3%
|