China's economic growth fell to a three-decade low last year. Official data shows the world's second-largest economy expanded by 6.6% over a year earlier, but down from 2017's 6.9%. Growth in the three months ending in December dipped to 6.4%. That's the lowest quarterly level since the 2008 global crisis. Exports held up through most of 2018 despite the tariff hikes on Chinese imports to the U.S., but they contracted in December as the penalties began to depress U.S. demand.