For centuries China stood as a leading civilization, outpacing the rest of the world in the arts and sciences, but in the 19th and early 20th centuries, the country was beset by civil unrest, major famines, military defeats, and foreign occupation. Foreign investment remains a strong element in China's remarkable expansion in world trade and has been an important factor in the growth of urban jobs. In July 2005, China revalued its currency by 2.1% against the US dollar and moved to an exchange rate system that references a basket of currencies. In 2006 China had the largest current account surplus in the world - nearly $180 billion. More power generating capacity came on line in 2006 as large scale investments were completed. Thirteen years in construction at a cost of $24 billion, the immense Three Gorges Dam across the Yangtze River was essentially completed in 2006 and will revolutionize electrification and flood control in the area. The 11th Five-Year Program (2006-10), approved by the National People's Congress in March 2006, calls for a 20% reduction in energy consumption per unit of GDP by 2010 and an estimated 45% increase in GDP by 2010. The plan states that conserving resources and protecting the environment are basic goals, but it lacks details on the policies and reforms necessary to achieve these goals.