China has steamed past Japan to become the world's second-largest economy. Japan's economy, hit by a drop in exports and consumer demand, was worth $5.5 trillion at the end of last year, while China's was estimated at $5.8 trillion. China is expected to take over the US as the No. 1 economy in about a decade, reports the BBC. Japan officials played down the news. "As an economy, we are not competing for rankings but working to improve citizens' lives," said the nation's economics minister. (More Japan stories.)