| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 5 |
0.2%
|
| -7 | Does not apply | 8 |
0.3%
|
| 0 | No obstacle | 2163 |
80.2%
|
| 1 | Minor obstacle | 336 |
12.5%
|
| 2 | Moderate obstacle | 130 |
4.8%
|
| 3 | Major obstacle | 35 |
1.3%
|
| 4 | Very severe obstacle | 20 |
0.7%
|