| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 0 | 
                                    
                                    0%
                                 | 
| -7 | Does not apply | 20 | 
                                    
                                    3.3%
                                 | 
| 0 | No obstacle | 172 | 
                                    
                                    28.1%
                                 | 
| 1 | Minor obstacle | 155 | 
                                    
                                    25.3%
                                 | 
| 2 | Moderate obstacle | 86 | 
                                    
                                    14.1%
                                 | 
| 3 | Major obstacle | 100 | 
                                    
                                    16.3%
                                 | 
| 4 | Very severe obstacle | 79 | 
                                    
                                    12.9%
                                 |