| Value | Category | Cases | |
|---|---|---|---|
| 1 | 1. Higher grade | 0 | 
                                                                 
                                    
                                    0%
                                 
                                                             | 
                                                        
                    
| 2 | 2. Standard grade | 0 | 
                                                                 
                                    
                                    0%
                                 
                                                             | 
                                                        
                    
| 3 | 3. Lower grade | 0 | 
                                                                 
                                    
                                    0%
                                 
                                                             | 
                                                        
                    
| 9 | 9. Don't know | 1 | 
                                                                 
                                    
                                    100%
                                 
                                                             | 
                                                        
                    
| Sysmiss | 98 |