| Value | Category | Cases | |
|---|---|---|---|
| -999 | -999 | 0 | 
                                                                 
                                    
                                    0%
                                 
                                                             | 
                                                        
                    
| -888 | -888 | 24 | 
                                                                 
                                    
                                    15%
                                 
                                                             | 
                                                        
                    
| 1 | More than one month | 15 | 
                                                                 
                                    
                                    9.4%
                                 
                                                             | 
                                                        
                    
| 2 | Once every month | 10 | 
                                                                 
                                    
                                    6.3%
                                 
                                                             | 
                                                        
                    
| 3 | Once every two months | 14 | 
                                                                 
                                    
                                    8.8%
                                 
                                                             | 
                                                        
                    
| 4 | Once every three months | 53 | 
                                                                 
                                    
                                    33.1%
                                 
                                                             | 
                                                        
                    
| 5 | Less than once every three months | 44 | 
                                                                 
                                    
                                    27.5%
                                 
                                                             | 
                                                        
                    
| Sysmiss | 752 |