| Value | Category | Cases | |
|---|---|---|---|
| 1 | NO DIFFICULTY | 19567 | 
                                                                 
                                    
                                    87.1%
                                 
                                                             | 
                                                        
                    
| 2 | SOME DIFFICULTY | 2482 | 
                                                                 
                                    
                                    11.1%
                                 
                                                             | 
                                                        
                    
| 3 | A LOT OF DIFFICULTY | 350 | 
                                                                 
                                    
                                    1.6%
                                 
                                                             | 
                                                        
                    
| 4 | CANNOT LEARN THINGS AT ALL | 48 | 
                                                                 
                                    
                                    0.2%
                                 
                                                             | 
                                                        
                    
| 9 | NO RESPONSE | 7 | 
                                                                 
                                    
                                    0%
                                 
                                                             | 
                                                        
                    
| Sysmiss | 252 |