By BridgeNews The productivity of the U.S. workforce continued to climb in the fourth quarter, but like overall economic growth, the rate of increase was slower than it has been. Productivity among U.S. non-farm workers grew at an annual rate of 2.4%, down from a revised 3.0% rate in the previous quarter, the Labor Dept. reported Feb. 7. Meanwhile, labor costs surged 4.1%, much faster than the revised annual rate of 3.2% the department reported for the third quarter. It was the fastest increase in labor costs since the second quarter of 1999.