The non-manufacturing purchasing managers' index (PMI) slipped for the second month on the trott in December, due to a slowdown in construction and service sectors, new data showed Friday. The non-manufacturing PMI declined to 54.6 percent last month from 56 percent in November and 56.3 percent in October, according to the National Bureau of Statistics (NBS) and the China Federation of Logistics and Purchasing (CFLP). The index tracks non-manufacturing sectors including construction, software, aviation, railway transport and real estate. A reading above 50 percent indicates expansion, while a reading below 50 percent reflects contraction. CFLP's vice chairman Cai Jin attributed the drop mainly to slowdown in the construction and service sectors near the end of the year. The sub-index for the service sector dropped 1.6 percentage points to 52.5 percent, while that for construction edged down 0.9 percentage point to 62.6 percent. "However, market demand remained relatively stable, as indicated by a flat index for new orders," Cai said. In December, the new orders index stayed at 51 percent, consistent with the previous month. The sub-index for new construction orders rose 2.1 percentage points to 55.9 percent, projecting strong demand for construction. The index for business outlook dropped 2.6 percentage points to 58.7 percent last month, indicating that fewer companies were optimistic about business prospects in the next three months, according to NBS data. The sub-index for prices charged by enterprises rose 2.5 percentage points to 52 percent, and that for intermediate inputs rose 2.1 percentage points to 56.9 percent. Cai said the rising prices were mainly due to the rise in prices of oil products and seasonal factors, but were not enough to show a rising trend for prices. PMI for China's manufacturing sector dropped slightly to 51 percent in December, down from 51.4 percent in November, signaling some downward pressure for the economy, according to NBS data released Wednesday. China's economy expanded by 7.7 percent in the first nine months of 2013, higher than the government's full-year target of 7.5 percent. GDP growth in the third quarter accelerated to 7.8 percent from 7.5 percent in the second.