| Value | Category | Cases | |
|---|---|---|---|
| -999 | -999 | 1 | 
                                                                 
                                    
                                    0.9%
                                 
                                                             | 
                                                        
                    
| -888 | -888 | 14 | 
                                                                 
                                    
                                    12.1%
                                 
                                                             | 
                                                        
                    
| 1 | More than one month | 8 | 
                                                                 
                                    
                                    6.9%
                                 
                                                             | 
                                                        
                    
| 2 | Once every month | 9 | 
                                                                 
                                    
                                    7.8%
                                 
                                                             | 
                                                        
                    
| 3 | Once every two months | 7 | 
                                                                 
                                    
                                    6%
                                 
                                                             | 
                                                        
                    
| 4 | Once every three months | 37 | 
                                                                 
                                    
                                    31.9%
                                 
                                                             | 
                                                        
                    
| 5 | Less than once every three months | 40 | 
                                                                 
                                    
                                    34.5%
                                 
                                                             | 
                                                        
                    
| Sysmiss | 796 |