| Value | Category | 
                                    
                    
                        | 1 | Grass | 
                                    
                    
                        | 2 | Iron sheets | 
                                    
                    
                        | 3 | Clay tiles | 
                                    
                    
                        | 4 | Concrete | 
                                    
                    
                        | 5 | Plastic sheeting | 
                                    
                    
                        | 6 | Other (specify) | 
                            
            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.