Housing conditions in rural areas varied widely.[1] During the 1960s and 1970s, thousands of production brigades built sturdy, sanitary houses and apartments and in many cases entire new villages.[1] With the introduction of the responsibility system and the more than doubling of rural incomes in the early 1980s, another wave of housing construction took place as farm families moved quickly to invest in their major personal assets – their homes – which for the most part were privately owned.[1] Many farm family houses lacked running water, but virtually all had electricity and were considerably more spacious than urban dwellings.[1] In 1980 farm homes averaged 9.4 square meters of living space per person, and by 1985 the figure had risen to 14.7 square meters.[1] Despite extensive construction of new housing, in poorer regions some farm families still lived in traditional dwellings, such as mud-brick and thatch houses or, in some regions, cave houses.[1] Many of the nomadic herders in Inner Mongolia, Xinjiang, and Xizang (Tibet) autonomous regions still lived in tents or felt yurts.[1] In the Yangtze River Valley and in south China, some fishing and boat transportation communities continued to live on their vessels.[1]