U.S. consumer credit increased at an annual rate of 6.7 percent in March, the largest monthly rise in a year, the U.S. Federal Reserve reported Wednesday. The total consumer borrowing rose to a seasonally adjusted 3.14 trillion U.S. dollars in March from a revised 3.12 trillion dollars in February, the largest gain since February 2013. Revolving debt, the type which includes credit cards, totaled 856.7 billion dollars in March, up 1.1 billion dollars, or 1.6 percent at an annual rate from the revised figure in February. It followed a 3.8 percent decline in the previous month. The borrowing in the non-revolving category that includes auto and student loans, climbed at an annual rate of 8.7 percent to 2. 28 trillion dollars. Consumer spending, which accounts for about 70 percent of the overall U.S. economic activity, is the major engine of U.S. economic growth. A rise in consumer credit indicated consumers boosted their borrowing on spending.