| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 0 | 
                                    
                                    0%
                                 | 
| -7 | Does not apply | 0 | 
                                    
                                    0%
                                 | 
| 0 | No obstacle | 237 | 
                                    
                                    65.1%
                                 | 
| 1 | Minor obstacle | 44 | 
                                    
                                    12.1%
                                 | 
| 2 | Moderate obstacle | 50 | 
                                    
                                    13.7%
                                 | 
| 3 | Major obstacle | 19 | 
                                    
                                    5.2%
                                 | 
| 4 | Very severe obstacle | 14 | 
                                    
                                    3.8%
                                 |