US consumer credit increased at an annual rate of 8 percent in August, following an unexpected decline in July, the US Federal Reserve announced on Friday. Total consumer borrowing rose from a revised 2.7075 trillion US dollars in July to 2.7256 trillion dollars in August, the central bank said in a report. Revolving debt, which includes credit cards, rose to 854.9 billion dollars in August from a revised 850.7 billion in July, representing an annual growth rate of 5.9 percent. In August, borrowing in the nonrevolving category, which includes auto and students loans, rose at an annual rate of 9 percent to 1.8707 trillion dollars. Consumer spending, which accounts for about 70 percent of the overall US economic activity, was a major engine of the US economic growth.