By John S. McClenahen As in manufacturing, business activity in the non-manufacturing sector of the U.S. economy increased in December, according to data released Jan. 5 by the Tempe, Ariz.-based Institute for Supply Management (ISM). Its non-manufacturing index was at 63.1%, up 1.8 percentage points from 61.3% in November. That's the index's highest level since the 64.8% recorded in July 2004. A figure above 50% generally indicates the non-manufacturing sector is expanding; a figure below 50% signals it is contracting. Both new orders and inventories increased faster in December than in November. Employment among non-manufacturers also increased in December, but at a slower pace than in November. The monthly ISM non-manufacturing index is based on data from more than 370 purchasing and supply executives in 62 industries including mining, construction, agriculture, and finance and banking.