| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 0 | 
                                    
                                    0%
                                 | 
| -7 | Does not apply | 1 | 
                                    
                                    0.2%
                                 | 
| 0 | No obstacle | 191 | 
                                    
                                    47.5%
                                 | 
| 1 | Minor obstacle | 44 | 
                                    
                                    10.9%
                                 | 
| 2 | Moderate obstacle | 39 | 
                                    
                                    9.7%
                                 | 
| 3 | Major obstacle | 52 | 
                                    
                                    12.9%
                                 | 
| 4 | Very severe obstacle | 75 | 
                                    
                                    18.7%
                                 |