industrial city. With 0.1% of the land area of the country, it supplies over 12% of the municipal revenue and handles more than a quarter of total trade passing through China's ports. Its year 2010 population, according to China's latest census, was 23.02 million and represented an increase of 6.61 million from the 2000 census. The average size of a family in Shanghai declined to fewer than three people during the 1990s, and it is clear that most of Shanghai's population growth is driven by migration rather than natural factors based on high birth and fertility rates. Shanghai has for many years had the lowest birth rate in China, a rate lower than large American cities such as New York. As with most cities in China, Shanghai is overbounded in its administrative territory. The city in the year 2010 was composed of 16 districts and one county, together occupying of land area. Chongming contains substantial rural land and a number of rural residents who continue to farm for their livelihood. The city has the highest population density of all the first-order administrative units in China, with 3630.5/km2 (9402.9/sq mi) in 2010. Owing to its continued growth and industrial and commercial development, Shanghai also has the highest index of urbanization among all of China's first order administrative units, with 89.3% of the official population (20.6 million) classified as urban. The amount of building activity in Shanghai fueled by government investment expenditures continues to be astounding. Since the 1980s, Shanghai's economy shifted from over 77% of gross domestic product in secondary sector manufacturing to a more balanced sectoral distribution of 48% in industry and 51% in services in 2000 and 2001. Employment in manufacturing reached almost 60% in 1990 and has declined steadily since to 41% in 2001, while employment in the tertiary sector has grown from 30% in 1990 to more than 47% in 2001. The rapid growth in population, factories and motor vehicles has generated environmental issues. Experts say the chief problems involve air and water pollution and the accumulation of solid wastes. See also Timeline of Shanghai history The Shanghai Document, a documentary film portraying Shanghai in the early 1920s Notes References Citations Sources Further reading Arkaraprasertkul, Non. "Power, politics, and the making of Shanghai." 'Journal of Planning History 9.4 (2010): 232-259, since 1980 Balfour, Alan and Zheng Zhiling, Shanghai (Chichester 2002). Bergère, Marie-Claire. Shanghai: China's Gateway to Modernity