Measuring inequality after accounting for taxes and transfers reduces observed inequality, because both the income tax system and transfer systems are designed to do so. The impacts of those polieices varies as the policy regime changes. CBO reported in 2011 that: "The equalizing effect of transfers declined over the 1979–2007 period primarily because the distribution of transfers became less progressive. The equalizing effect of federal taxes also declined over the period, in part because the amount of federal taxes shrank as a share of market income and in part because of changes in the progressivity of the federal tax system."