| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 0 | 
                                    
                                    0%
                                 | 
| -7 | Does not apply | 12 | 
                                    
                                    1.3%
                                 | 
| 0 | No obstacle | 559 | 
                                    
                                    58.5%
                                 | 
| 1 | Minor obstacle | 175 | 
                                    
                                    18.3%
                                 | 
| 2 | Moderate obstacle | 123 | 
                                    
                                    12.9%
                                 | 
| 3 | Major obstacle | 55 | 
                                    
                                    5.8%
                                 | 
| 4 | Very severe obstacle | 31 | 
                                    
                                    3.2%
                                 |