| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 34 | 
                                    
                                    5.6%
                                 | 
| -7 | Does not apply | 47 | 
                                    
                                    7.7%
                                 | 
| 0 | No obstacle | 323 | 
                                    
                                    52.8%
                                 | 
| 1 | Minor obstacle | 117 | 
                                    
                                    19.1%
                                 | 
| 2 | Moderate obstacle | 61 | 
                                    
                                    10%
                                 | 
| 3 | Major obstacle | 17 | 
                                    
                                    2.8%
                                 | 
| 4 | Very severe obstacle | 13 | 
                                    
                                    2.1%
                                 |