| Value | Category | 
                                    
                    
                        | 1 | public network | 
                                    
                    
                        | 2 | own ntework | 
                                    
                    
                        | 3 | nat gas stove | 
                                    
                    
                        | 4 | wood/coal/disel fuel stove | 
                                    
                    
                        | 5 | elec heater | 
                                    
                    
                        | 6 | no | 
                            
            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.