| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 1 | 
                                    
                                    0.3%
                                 | 
| -7 | Does not apply | 2 | 
                                    
                                    0.6%
                                 | 
| 0 | No obstacle | 176 | 
                                    
                                    48.5%
                                 | 
| 1 | Minor obstacle | 52 | 
                                    
                                    14.3%
                                 | 
| 2 | Moderate obstacle | 62 | 
                                    
                                    17.1%
                                 | 
| 3 | Major obstacle | 59 | 
                                    
                                    16.3%
                                 | 
| 4 | Very severe obstacle | 11 | 
                                    
                                    3%
                                 |