Growth in non-manufacturing economic activity continued to diminish in December, after slipping more than anticipated in the prior month.

The measure of economic movement in the service sector fell to 55.9, below the expected level of 57.6 forecast by a survey of Reuters economists.

While the growth rate slipped, the December numbers represent the 96th consecutive month of economic growth in the service sector.

The index measures non-manufacturing activity in 17 industries, such as real estate, construction and mining. A reading above 50 for the index indicates expansion in the service sector, and a reading below 50 signals contraction.