| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 0 | 
                                    
                                    0%
                                 | 
| -7 | Does not apply | 3 | 
                                    
                                    0.3%
                                 | 
| 0 | No obstacle | 715 | 
                                    
                                    69.8%
                                 | 
| 1 | Minor obstacle | 208 | 
                                    
                                    20.3%
                                 | 
| 2 | Moderate obstacle | 70 | 
                                    
                                    6.8%
                                 | 
| 3 | Major obstacle | 23 | 
                                    
                                    2.2%
                                 | 
| 4 | Very severe obstacle | 5 | 
                                    
                                    0.5%
                                 |