| Value | Category | 
                                    
                    
                        | -99 | Dont know | 
                                    
                    
                        | -95 |  | 
                                    
                    
                        | 1 | 1-2 times | 
                                    
                    
                        | 2 | once in 3 m | 
                                    
                    
                        | 3 | almost monthly | 
                                    
                    
                        | 4 | Twice a month or more | 
                                    
                    
                        | Sysmiss |  | 
                            
            Warning: these figures indicate the number of cases found in the data file. They cannot be interpreted as summary statistics of the population of interest.