| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 3 | 
                                    
                                    2.7%
                                 | 
| -7 | Does not apply | 1 | 
                                    
                                    0.9%
                                 | 
| 0 | No obstacle | 54 | 
                                    
                                    48.6%
                                 | 
| 1 | Minor obstacle | 36 | 
                                    
                                    32.4%
                                 | 
| 2 | Moderate obstacle | 7 | 
                                    
                                    6.3%
                                 | 
| 3 | Major obstacle | 10 | 
                                    
                                    9%
                                 | 
| 4 | Very severe obstacle | 0 | 
                                    
                                    0%
                                 |