of the Economic Recovery Tax Act of 1981, which lowered the top marginal tax bracket from 70% to 50% and the lowest bracket from 14% to 11%. This act slashed estate taxes and trimmed taxes paid by business corporations by $150 billion over a five-year period. In 1982 Reagan agreed to a rollback of corporate tax cuts and a smaller rollback of individual income tax cuts. The 1982 tax increase undid a third of the initial tax cut. In 1983 Reagan instituted a payroll tax increase on Social Security and Medicare hospital insurance. In 1984 another bill was introduced that closed tax loopholes. According to tax historian Joseph Thorndike, the bills of 1982 and 1984 "constituted the biggest tax increase ever enacted during peacetime". With the Tax Reform Act of 1986, Reagan and Congress sought to simplify the tax system by eliminating many deductions, reducing the highest marginal rates, and reducing the number of tax brackets. In 1983, Democrats Bill Bradley and Dick Gephardt had offered a proposal; in 1984 Reagan had the Treasury Department produce its own plan. The 1986 act aimed to be revenue-neutral: while it reduced the top marginal rate, it also cleaned up the tax base by removing certain tax write-offs, preferences, and exceptions, thus raising the effective tax on activities previously specially favored by the code. Ultimately, the combination of the decrease in deductions and decrease in rates raised revenue equal to about 4% of existing tax revenue. Federal revenue share of GDP fell from 19.6% in fiscal 1981 to 17.3% in 1984, before rising back to 18.4% by fiscal year 1989. Personal income tax revenues fell during this period relative to GDP, while payroll tax revenues rose relative to GDP. Reagan's 1981 cut in the top regular tax rate on unearned income reduced the maximum capital gains rate to only 20% – its lowest level since the Hoover administration. The 1986 act set tax rates on capital gains at the same level as the rates on ordinary income like salaries and wages, with both topping out at 28%. Reagan significantly increased public expenditures, primarily the Department of Defense, which rose (in constant 2000 dollars) from $267.1 billion in 1980 (4.9% of GDP and 22.7% of public expenditure) to $393.1 billion in 1988 (5.8% of GDP and 27.3% of public expenditure); most of those years military spending was about 6% of GDP, exceeding this number