Economic activity in Mongolia has long been based on herding and agriculture, although development of extensive mineral deposits of copper, coal, molybdenum, tin, tungsten and gold have emerged as a driver of industrial production. Besides mining (21.8% of GDP) and agriculture (16% of GDP), dominant industries in the composition of GDP are wholesale and retail trade and service, transportation and storage, and real estate activities. The informal economy is estimated to be at least one-third the size of the official economy. , 68.4% of Mongolia's exports went to the PRC, and the PRC supplied 29.8% of Mongolia's imports.