| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 0 | 
                                    
                                    0%
                                 | 
| -7 | Does not apply | 5 | 
                                    
                                    1.4%
                                 | 
| 0 | No obstacle | 212 | 
                                    
                                    58.2%
                                 | 
| 1 | Minor obstacle | 31 | 
                                    
                                    8.5%
                                 | 
| 2 | Moderate obstacle | 59 | 
                                    
                                    16.2%
                                 | 
| 3 | Major obstacle | 44 | 
                                    
                                    12.1%
                                 | 
| 4 | Very severe obstacle | 13 | 
                                    
                                    3.6%
                                 |