Trader is reflected in a screen as he works on the floor of the New York Stock exchange in New YorkBy means of Chuck Mikolajczak NEW YORK (Reuters) – U.S. shares declined on Thursday as investors opened the 12 months on a cautious observe after the S&P 500 wrapped up its highest year on account that 1997, despite financial data pointing to continued growth in the economic system. The Institute for Supply Administration said its index of national manufacturing facility process stood at fifty seven.zero last month, in line with economists' forecasts but a marginally under November's 2-half-year high of fifty seven.three.