| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 12 | 
                                    
                                    3.9%
                                 | 
| -7 | Does not apply | 76 | 
                                    
                                    24.4%
                                 | 
| 0 | No obstacle | 163 | 
                                    
                                    52.4%
                                 | 
| 1 | Minor obstacle | 22 | 
                                    
                                    7.1%
                                 | 
| 2 | Moderate obstacle | 17 | 
                                    
                                    5.5%
                                 | 
| 3 | Major obstacle | 11 | 
                                    
                                    3.5%
                                 | 
| 4 | Very severe obstacle | 10 | 
                                    
                                    3.2%
                                 |