| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 3 | 
                                    
                                    0.7%
                                 | 
| -7 | Does not apply | 7 | 
                                    
                                    1.7%
                                 | 
| 0 | No obstacle | 177 | 
                                    
                                    43.3%
                                 | 
| 1 | Minor obstacle | 68 | 
                                    
                                    16.6%
                                 | 
| 2 | Moderate obstacle | 107 | 
                                    
                                    26.2%
                                 | 
| 3 | Major obstacle | 29 | 
                                    
                                    7.1%
                                 | 
| 4 | Very severe obstacle | 18 | 
                                    
                                    4.4%
                                 | 
| Sysmiss | 546 |