TORONTO - Canada's main stock index pushed higher in its first day of trading for the year, boosted by gains in the materials, energy and health-care sectors. The S&P/TSX composite index was up 52.95 points to 16,262.08, after 90 minutes of trading. In New York, the Dow Jones industrial average was up 59.57 points to 24,778.79. The S&P 500 index was up 16.46 points to 2,690.07 and the Nasdaq composite index was up 81.97 points to 6,985.36. ...