| Value | Category | Cases | |
|---|---|---|---|
| 1 | NO DIFFICULTY | 4815 | 
                                    
                                    87.9%
                                 | 
| 2 | SOME DIFFICULTY | 472 | 
                                    
                                    8.6%
                                 | 
| 3 | A LOT OF DIFFICULTY | 59 | 
                                    
                                    1.1%
                                 | 
| 4 | CANNOT SEE AT ALL | 10 | 
                                    
                                    0.2%
                                 | 
| 9 | NO RESPONSE | 3 | 
                                    
                                    0.1%
                                 | 
| Sysmiss | 120 | 
                                    
                                    2.2%
                                 |