| Value | Category | 
                                    
                    
                        | 1 | Electricity | 
                                    
                    
                        | 2 | Gas from networks | 
                                    
                    
                        | 3 | Gas in container | 
                                    
                    
                        | 4 | Coal, wood, solid fuel | 
                                    
                    
                        | 5 | Black or heating oil | 
                                    
                    
                        | 6 | 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.