| Value | Category | Cases | |
|---|---|---|---|
| 1 | 1. higher grade | 0 | 
                                                                 
                                    
                                    0%
                                 
                                                             | 
                                                        
                    
| 2 | 2. standard grade | 0 | 
                                                                 
                                    
                                    0%
                                 
                                                             | 
                                                        
                    
| 3 | 3. lower grade | 0 | 
                                                                 
                                    
                                    0%
                                 
                                                             | 
                                                        
                    
| 7 | 7. did not take | 1 | 
                                                                 
                                    
                                    25%
                                 
                                                             | 
                                                        
                    
| 9 | 9. don't know | 3 | 
                                                                 
                                    
                                    75%
                                 
                                                             | 
                                                        
                    
| Sysmiss | 995 |