By John S. McClenahen In contrast to U.S. manufacturing's dramatic rate of growth during December 2002, the service sector's rate of growth slowed. Business activity, as measured by Tempe, Ariz.-based Institute for Supply Management's non-manufacturing index, was 54.7% last month, still expanding but nearly three percentage points lower than November's 57.4% rate. December's index also was below the 55% that economists generally expected. Nevertheless, "the reading was high enough to suggest that the overall [U.S.] economy is climbing out of its soft patch," says Maury Harris, chief U.S. economist at UBS Warburg LLC, New York. A figure above 50% indicates that the non-manufacturing sector of the economy is expanding; below 50%, it signals contraction.