| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 3 |
0.2%
|
| -7 | Does not apply (spontaneous) | 45 |
2.9%
|
| 0 | No obstacle | 1470 |
93.5%
|
| 1 | Minor obstacle | 35 |
2.2%
|
| 2 | Moderate obstacle | 16 |
1%
|
| 3 | Major obstacle | 3 |
0.2%
|
| 4 | Very severe obstacle | 1 |
0.1%
|