| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 3 |
0.2%
|
| -7 | Does not apply | 12 |
0.7%
|
| 0 | No obstacle | 693 |
41.7%
|
| 1 | Minor obstacle | 228 |
13.7%
|
| 2 | Moderate obstacle | 323 |
19.4%
|
| 3 | Major obstacle | 191 |
11.5%
|
| 4 | Very severe obstacle | 213 |
12.8%
|