| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 0 | 
                                    
                                    0%
                                 | 
| -7 | Does not apply | 2 | 
                                    
                                    0.5%
                                 | 
| 0 | No obstacle | 187 | 
                                    
                                    51.4%
                                 | 
| 1 | Minor obstacle | 38 | 
                                    
                                    10.4%
                                 | 
| 2 | Moderate obstacle | 82 | 
                                    
                                    22.5%
                                 | 
| 3 | Major obstacle | 37 | 
                                    
                                    10.2%
                                 | 
| 4 | Very severe obstacle | 18 | 
                                    
                                    4.9%
                                 |