| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 6 | 
                                    
                                    5.4%
                                 | 
| -7 | Does not apply | 0 | 
                                    
                                    0%
                                 | 
| 0 | No obstacle | 43 | 
                                    
                                    38.7%
                                 | 
| 1 | Minor obstacle | 31 | 
                                    
                                    27.9%
                                 | 
| 2 | Moderate obstacle | 16 | 
                                    
                                    14.4%
                                 | 
| 3 | Major obstacle | 13 | 
                                    
                                    11.7%
                                 | 
| 4 | Very severe obstacle | 2 | 
                                    
                                    1.8%
                                 |