U.S. gross domestic product grew by 3.3% in the second quarter - much more than previously stated. Economists say the economic stimulus package contributed to the rise. NEW YORK (CNNMoney.com) -- A revised reading on gross domestic product announced Thursday showed much better U.S. economic growth than previously reported for the second quarter. GDP, the broadest measure of the nation's economic activity, stood at an annual rate of 3.3% in the quarter, adjusted for inflation, the Commerce Department said. The revised results far surpassed the initial advanced estimate of 1.9% released late last month, which disappointed economists. Many experts say the more than $90 billion in economic stimulus checks that reached taxpayers during the quarter helped boost GDP up from just 0.9% growth in the previous quarter. Economists surveyed on Briefing.com expected the revised reading to show the economy grew at an annual rate of 2.7% in the second quarter.