The U.S. service sector picked up momentum in January, reversing a slowdown at the end of 2017. The Institute for Supply Management on Monday said its nonmanufacturing index rose by more than four points to 59.9 in January, a far stronger reading than the 56.6 expected by economists. In December, the index slipped to 55.9. January’s figure is the highest in 13 years. A reading above 50 indicates that non-manufacturing business is expanding, while a reading below signals contraction. The survey tracks the performance of service-oriented companies, such as banks and restaurants, as well as real estate and construction. Fifteen of the 18 business sectors tracked by ISM experienced growth in January. ISM’s gauge of non-manufacturing employment rose to an all-time high of 61.6, up from 56.3 in December. Its index of new orders surged 8.2 percentage points to 62.7. The survey shows that the economy is off to a strong start in 2018.