It is now a foregone conclusion that China’s economy will become the biggest in the world sometime very soon. According to the World Bank, the size of China’s economy is $10.1 trillion, compared with $14.6 trillion for the U.S., based on purchasing power parity (which adjusts exchange rates to account for the different prices people pay for goods and services across countries). But China is narrowing the gap in a hurry. Over the past 10 years, the annual real growth of China’s gross domestic product averaged 10.5 percent, compared with 1.7 percent in the U.S.