And here are the tax laws ordered from highest to lowest as a percentage of GDP:

 

Tax bill	Percentage of GDP
Economic Recovery Tax Act of 1981	2.89 percent
Revenue Act of 1945	2.67 percent
Revenue Act of 1948	1.87 percent
American Taxpayer Relief Act of 2012 (enacted in 2013)	1.78 percent
Revenue Act of 1964	1.6 percent
Tax Relief, Unemployment Insurance Reauthorization, and Job Creation Act of 2010	1.31 percent
Current tax proposal	0.8 percent-1.2 percent
Revenue Act of 1978	0.8 percent