| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 9 | 
                                    
                                    1.4%
                                 | 
| -7 | Does not apply | 36 | 
                                    
                                    5.6%
                                 | 
| 0 | No obstacle | 179 | 
                                    
                                    27.8%
                                 | 
| 1 | Minor obstacle | 162 | 
                                    
                                    25.1%
                                 | 
| 2 | Moderate obstacle | 138 | 
                                    
                                    21.4%
                                 | 
| 3 | Major obstacle | 78 | 
                                    
                                    12.1%
                                 | 
| 4 | Very severe obstacle | 43 | 
                                    
                                    6.7%
                                 |