| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 0 | 
                                    
                                    0%
                                 | 
| -7 | Does not apply | 34 | 
                                    
                                    5.6%
                                 | 
| 0 | No obstacle | 238 | 
                                    
                                    38.9%
                                 | 
| 1 | Minor obstacle | 113 | 
                                    
                                    18.5%
                                 | 
| 2 | Moderate obstacle | 90 | 
                                    
                                    14.7%
                                 | 
| 3 | Major obstacle | 75 | 
                                    
                                    12.3%
                                 | 
| 4 | Very severe obstacle | 62 | 
                                    
                                    10.1%
                                 |