| Value | Category | 
                                    
                    
                        | 10 | NATURAL | 
                                    
                    
                        | 20 | RUDIMENTARY | 
                                    
                    
                        | 21 | Dirt, clay | 
                                    
                    
                        | 30 | FINISHED | 
                                    
                    
                        | 31 | Cement | 
                                    
                    
                        | 32 | Plain tile | 
                                    
                    
                        | 33 | Plaster | 
                                    
                    
                        | 34 | Stone | 
                                    
                    
                        | 35 | Marble | 
                                    
                    
                        | 96 | Other | 
                            
            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.