Only about one of five Sinhalese lives in a city; Sri Lanka is still predominantly rural country, and—unlike most Third World countries—its rural-urban balance has not changed significantly in this century. Educational and medical facilities are available in most rural areas and a very low rate of industrialization gives rural villagers little reason to migrate to the cities. In the traditional "one village, one tank" pattern, the village ( gama ) is situated downstream from an artificial reservoir. Ringed around the paddy fields are the traditional two-to four-room houses, each situated in its own garden and separated from others. Traditional houses are made of mud and plaster and thatched with woven palm fronds. Wealthier villagers construct stucco houses roofed with ceramic tiles.