Washington, Rabi'II 25, 1437, February 04, 2016, SPA -- U.S. productivity fell sharply in the final three months of 2015, closing out a fifth straight year of weak gains in worker efficiency. The Labor Department says productivity, the amount of output per hour of work, fell at an annual rate of 3 percent in the fourth quarter. It was the biggest quarterly decline in nearly two years. Labor costs rose 4.5 percent in the fourth quarter but were up a more modest 2.4 percent for the year. Productivity last year edged up a slight 0.6 percent after a tiny 0.7 percent gain in 2014. It has been weak since 2011, a troubling development given that productivity is a key ingredient needed for rising living standards. --SPA 16:52 LOCAL TIME 13:52 GMT www.spa.gov.sa/w