"From the founding of the Republic to 1929, spending by governments at all levels, federal, state, and local never exceeded 12 percent of the national income except in time of major war, and two-thirds of that was state and local spending. Federal spending typically amounted to 3 percent or less of the national income. Since 1933 government spending has never been less than 20 percent of national income and is now over 40 percent and two-thirds of that is spending by the federal government."
--From Milton Friedman's book "Free to Choose"
That was in 1980. In 2008, government spending accounted for about 45% of the national income. And today? I'm afraid to learn the answer when the current administration gets done with it.