| Value | Category | 
                                    
                    
                        | 0 | NIU (not in universe) | 
                                    
                    
                        | 10 | None | 
                                    
                    
                        | 20 | Electricity | 
                                    
                    
                        | 30 | Petroleum gas, unspecified | 
                                    
                    
                        | 31 | Gas -- piped/utility | 
                                    
                    
                        | 32 | Gas -- tanked or bottled | 
                                    
                    
                        | 33 | Propane | 
                                    
                    
                        | 35 | Liquefied petroleum gas | 
                                    
                    
                        | 40 | Petroleum liquid | 
                                    
                    
                        | 41 | Oil, kerosene, and other liquid fuels | 
                                    
                    
                        | 42 | Kerosene/paraffin | 
                                    
                    
                        | 43 | Kerosene or oil | 
                                    
                    
                        | 44 | Kerosene or gasoline | 
                                    
                    
                        | 45 | Gasoline | 
                                    
                    
                        | 46 | Cocinol | 
                                    
                    
                        | 50 | Wood, coal, and other solid fuels | 
                                    
                    
                        | 51 | Wood and other plant fuels | 
                                    
                    
                        | 52 | Non-wood plant materials | 
                                    
                    
                        | 53 | Coal or charcoal | 
                                    
                    
                        | 54 | Charcoal | 
                                    
                    
                        | 55 | Coal | 
                                    
                    
                        | 56 | Wood or charcoal | 
                                    
                    
                        | 60 | Multiple fuels | 
                                    
                    
                        | 61 | Bottled gas and wood | 
                                    
                    
                        | 62 | Propane and electricity | 
                                    
                    
                        | 63 | Propane, kerosene, and electricity | 
                                    
                    
                        | 64 | Propane and kerosene | 
                                    
                    
                        | 65 | Kerosene and electrictiy | 
                                    
                    
                        | 66 | Other combinations | 
                                    
                    
                        | 70 | Other | 
                                    
                    
                        | 71 | Alcohol | 
                                    
                    
                        | 72 | Biogas | 
                                    
                    
                        | 73 | Discarded or waste material | 
                                    
                    
                        | 74 | Dung/manure | 
                                    
                    
                        | 75 | Dung or grass | 
                                    
                    
                        | 76 | Solar energy | 
                                    
                    
                        | 77 | Candle | 
                                    
                    
                        | 99 | Unknown/missing | 
                            
            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.