| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 0 | 
                                    
                                    0%
                                 | 
| -7 | Does not apply | 11 | 
                                    
                                    1.1%
                                 | 
| 0 | No obstacle | 750 | 
                                    
                                    73.2%
                                 | 
| 1 | Minor obstacle | 151 | 
                                    
                                    14.7%
                                 | 
| 2 | Moderate obstacle | 46 | 
                                    
                                    4.5%
                                 | 
| 3 | Major obstacle | 48 | 
                                    
                                    4.7%
                                 | 
| 4 | Very severe obstacle | 18 | 
                                    
                                    1.8%
                                 |