Because this figure was much
underestimated. In fact, China 2013 physical GDP per capita was about 60% of the US counterpart (see the CIA World Factbook), about $5600 US; Using this figure times 5, you will get $28000 - that was the China 2013 GDP per capita. Otherwise, it is hard to explain the economic phenomena and scale of China.
1. In 2013, China produced 56% of iron and steel of the world.
2.In 2013, China consumed 60% of cement of the world.
3. In 2013, A Chinese people consumed more meat than an American did.
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