| Value | Category | 
                                    
                    
                        | 1 | 1. Never | 
                                    
                    
                        | 2 | 2. Once only | 
                                    
                    
                        | 3 | 3. A few times | 
                                    
                    
                        | 4 | 4. Often | 
                                    
                    
                        | 8 | 8. Not applicable | 
                                    
                    
                        | 99 | 99. No response | 
                            
            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.