The home front was subject to dynamic social changes throughout the war, though domestic issues were no longer Roosevelts most urgent policy concern. The military buildup spurred economic growth. Unemployment fell in half from 7.7 million in spring 1940 to 3.4 million in fall 1941 and fell in half again to 1.5 million in fall 1942, out of a labor force of 54 million. There was a growing labor shortage, accelerating the second wave of the Great Migration (African American) of African Americans, farmers and rural populations to manufacturing centers. African Americans from the South went to California and other West Coast states for new jobs in the defense industry. To pay for increased government spending, in 1941 Roosevelt proposed that Congress enact an income tax rate of 99.5% on all income over $100,000; when the proposal failed, he issued an executive order imposing an income tax of 100% on income over $25,000, which Congress rescinded. The Revenue Act of 1942 instituted top tax rates as high as 94% (after accounting for the excess profits tax), greatly increased the tax base, and instituted the first federal withholding tax. In 1944, Roosevelt requested that Congress enact legislation which would tax all "unreasonable" profits, both corporate and individual, and thereby support his declared need for over $10 billion in revenue for the war and other government measures. Congress overrode Roosevelts veto to pass a Individual Income Tax Act of 1944 raising $2 billion.
Question: How many million did the unemployment rate fall between spring 1940 and fall 1941?
Answer: 4.3