| Value | Category | Cases | |
|---|---|---|---|
| 1 | Monthly | 152 | 
                                    
                                    22%
                                 | 
| 2 | Quarterly | 345 | 
                                    
                                    50%
                                 | 
| 3 | Twice a year | 116 | 
                                    
                                    16.8%
                                 | 
| 4 | Annually | 77 | 
                                    
                                    11.2%
                                 | 
| Sysmiss | 90 |