A 2008 OECD study ranked 24 OECD nations by progressiveness of taxes and separately by progressiveness of cash transfers, which include pensions, unemployment and other benefits. The United States had the highest "concentration coefficient" in income tax, a measure of progressiveness, before adjusting for income inequality. The United States was not at the top of either measure for cash transfers. Adjusting for income inequality, Ireland had the highest concentration coefficient for income taxes. In 2008, overall income tax rates for the US were below the OECD average.