| Value | Category | Cases | |
|---|---|---|---|
| 0 | 4 | 
                                                                 
                                    
                                    26.7%
                                 
                                                             | 
                                                        
                    |
| 10 | 2 | 
                                                                 
                                    
                                    13.3%
                                 
                                                             | 
                                                        
                    |
| 15 | 1 | 
                                                                 
                                    
                                    6.7%
                                 
                                                             | 
                                                        
                    |
| 30 | 6 | 
                                                                 
                                    
                                    40%
                                 
                                                             | 
                                                        
                    |
| 40 | 1 | 
                                                                 
                                    
                                    6.7%
                                 
                                                             | 
                                                        
                    |
| 55 | 1 | 
                                                                 
                                    
                                    6.7%
                                 
                                                             | 
                                                        
                    |
| Sysmiss | don't know | 0 | |
| Sysmiss | refusal | 0 |