| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 3 | 
                                    
                                    0.7%
                                 | 
| -7 | Does not apply | 14 | 
                                    
                                    3.4%
                                 | 
| 0 | No obstacle | 244 | 
                                    
                                    59.7%
                                 | 
| 1 | Minor obstacle | 71 | 
                                    
                                    17.4%
                                 | 
| 2 | Moderate obstacle | 60 | 
                                    
                                    14.7%
                                 | 
| 3 | Major obstacle | 10 | 
                                    
                                    2.4%
                                 | 
| 4 | Very severe obstacle | 7 | 
                                    
                                    1.7%
                                 | 
| Sysmiss | 546 |