| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 5 | 
                                    
                                    0.4%
                                 | 
| -7 | Does not apply | 1 | 
                                    
                                    0.1%
                                 | 
| 0 | No obstacle | 865 | 
                                    
                                    61.1%
                                 | 
| 1 | Minor obstacle | 227 | 
                                    
                                    16%
                                 | 
| 2 | Moderate obstacle | 172 | 
                                    
                                    12.1%
                                 | 
| 3 | Major obstacle | 85 | 
                                    
                                    6%
                                 | 
| 4 | Very severe obstacle | 61 | 
                                    
                                    4.3%
                                 |