| Value | Category | 
                                    
                    
                        | 0 | *no more acquisition modes recorded | 
                                    
                    
                        | 1 | Purchased | 
                                    
                    
                        | 2 | Payment for services | 
                                    
                    
                        | 3 | Received as a gift | 
                                    
                    
                        | 4 | Other | 
                                    
                    
                        | 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.