WASHINGTON, Jan. 5 (Xinhua) -- The U.S. service sector expanded in December for the 12th consecutive month, providing fresh evidence of an ongoing U.S. economic recovery, an industry research group reported Wednesday.

The Non-Manufacturing Index (NMI), which measures activity in the service sector, rose to 57.1 percent last month from 55 percent in November, the Institute for Supply Management (ISM) said in its monthly survey of the nation's service sector.

A reading above 50 percent indicates a general expansion of the sector.

The index is closely watched because the service sector absorbs about 80 percent of the U.S. non-farm workforce, and is a key indicator for the overall health of the economy and labor market.

The index showed that new orders, a signal of future business, rose to 63 percent in December from 57.7 percent in November. But the survey's employment component dipped to 50.5 percent in December from 52.7 percent in November.

Altogether 14 industries reported growth in December, including real estate, utilities and others, while agriculture and educational services were among the three industries that reported contractions, according to the report.