WASHINGTON — U.S. employers added 148,000 jobs in December, a modest gain but still enough to suggest that the economy entered the new year with solid momentum.The unemployment rate remained 4.1 percent for a third straight month, the lowest level since 2000. For all of 2017, employers added nearly 2.1 million jobs, enough to lower the unemployment rate from 4.7 percent a year ago.Taken as a whole, Friday’s government report points to the job market’s strength and resilience 8 1/2 years into an economic expansion. Job growth remains steady and is underpinning an economy that’s both contributing to and benefiting from an improved global outlook. The just-enacted U.S. tax cuts, too, are raising hopes for faster growth and higher corporate profits and fueling a powerful stock market rally.At the same time, the pace of job growth is slowing, which typically happens when unemployment falls to ultra-low levels and fewer people are available to be hired. Average monthly job gains have declined to 171,000 this year from a peak of 250,000 in 2014. Last year’s job gains were the fewest since 2010.Despite the low unemployment and the difficulty some employers face in finding enough qualified workers, pay gains remain sluggish. Average hourly earnings rose 2.5 percent in December from a year earlier — about a full percentage point lower than is typical in a healthy economy.