| Value | Category | Cases | |
|---|---|---|---|
| 1 | No difficulty | 4973 | 
                                                                 
                                    
                                    79.4%
                                 
                                                             | 
                                                        
                    
| 2 | Some difficulty | 1137 | 
                                                                 
                                    
                                    18.2%
                                 
                                                             | 
                                                        
                    
| 3 | A lot of difficulty | 139 | 
                                                                 
                                    
                                    2.2%
                                 
                                                             | 
                                                        
                    
| 4 | Cannot see at all | 1 | 
                                                                 
                                    
                                    0%
                                 
                                                             | 
                                                        
                    
| 9 | No response | 12 | 
                                                                 
                                    
                                    0.2%
                                 
                                                             | 
                                                        
                    
| Sysmiss | 2271 |