WASHINGTON, Jan 29 (Reuters) – U.S. worker productivity grew at its fastest pace in two years in the third quarter, the government confirmed on Thursday, likely fueled by an artificial intelligence spending boom. Nonfarm productivity, which measures hourly output per worker, increased at an unrevised 4.9% annualized rate, the Labor Department’s Bureau of Labor Statistics said on Thursday. Economists polled by Reuters had expected third-quarter productivity growth would be unrevised. Productivity growth in the April-June quarter was also unrevised at a 4.1% pace. Productivity grew at an unrevised 1.9% rate from a year ago.