U.S. labor costs rose less than expected in the fourth quarter, leading to the smallest annual increase in two years, signs of moderating wage inflation that could give the Federal Reserve room to start cutting interest rates by June. Compensation costs growth is slowing as labor market conditions ease in response to the U.S. central bank's tight monetary policy stance. Government data on Tuesday showed Americans were becoming less enthusiastic about job-hopping, with the number of people quitting their jobs near a three-year low in December, a trend that could further slow wage inflation.