| Value | Category | Cases | |
|---|---|---|---|
| 1 | No-no difficulty | 68826 | 
                                    
                                    97.3%
                                 | 
| 2 | Yes-some difficulty | 1042 | 
                                    
                                    1.5%
                                 | 
| 3 | Yes- a lot of difficulty | 774 | 
                                    
                                    1.1%
                                 | 
| 4 | can not do at all | 86 | 
                                    
                                    0.1%
                                 | 
| Sysmiss | 11050 |