A report published by the OECD in 2008 presented empirical research showing a weak negative relationship between the progressivity of personal income taxes and economic growth.[1] Describing the research, William McBride, a staff writer with the conservative Tax Foundation, stated that progressivity of income taxes can undermine investment, risk-taking, entrepreneurship, and productivity because high-income earners tend to do much of the saving, investing, risk-taking, and high-productivity labor.[31][32] According to IMF, some advanced economies could increase progressivity in taxation for tackling inequality, without hampering growth, as long as progressivity is not excessive. Fund also states that the average top income tax rate for OECD member countries fell from 62 percent in 1981 to 35 percent in 2015, and that in addition, tax systems are less progressive than indicated by the statutory rates, because wealthy individuals have more access to tax relief.[33]