Economic growth in the world's second largest economy slowed down in the last quarter of 2013 as industrial output, retail sales and investments recorded declines suggesting that the economy lost its momentum, a report published by the National Bureau of Statistics showed on Monday. China's gross domestic product added 7.7% in the whole 2013, the least since 1999, while it also gained 7.7% year-on-year in the Q4 of 2013.