| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 9 |
0.5%
|
| -7 | Does not apply | 23 |
1.4%
|
| 0 | No obstacle | 279 |
16.8%
|
| 1 | Minor obstacle | 191 |
11.5%
|
| 2 | Moderate obstacle | 680 |
40.9%
|
| 3 | Major obstacle | 319 |
19.2%
|
| 4 | Very severe obstacle | 162 |
9.7%
|