| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 0 | 
                                    
                                    0%
                                 | 
| -7 | Does not apply | 0 | 
                                    
                                    0%
                                 | 
| 0 | No obstacle | 30 | 
                                    
                                    19.1%
                                 | 
| 1 | Minor obstacle | 72 | 
                                    
                                    45.9%
                                 | 
| 2 | Moderate obstacle | 43 | 
                                    
                                    27.4%
                                 | 
| 3 | Major obstacle | 9 | 
                                    
                                    5.7%
                                 | 
| 4 | Very severe obstacle | 3 | 
                                    
                                    1.9%
                                 |