| Value | Category | 
                                    
                    
                        | 0 | 3 times or less per term | 
                                    
                    
                        | 1 | 2-3 times per month | 
                                    
                    
                        | 2 | Once or more per week | 
                                    
                    
                        | 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.