the twentieth century, the United States fared better than the rest of the combatants because none of the First World War and relatively little of the Second World War were fought on American territory (and none on the then-48 states). Yet, even in the United States, the wars meant sacrifice. During the peak of Second World War activity, nearly 40 percent of U.S. GDP was devoted to war production. Decisions about large swaths of the economy were largely made for military purposes, and nearly all relevant inputs were allocated to the war effort. Many goods were rationed, prices and wages controlled, and many durable consumer goods were no longer produced. Large segments of the workforce were inducted into the military and paid half their wages; roughly half of those were sent into harm's way. The approach, advanced by British economist John Maynard Keynes, gave elected officials a leading role in directing the economy since spending and taxes are controlled by the U.S. president and Congress. The "Baby Boom" saw a dramatic increase in fertility in the period 1942–1957; it was caused by delayed marriages and childbearing during the depression years, a surge in prosperity, a demand for suburban single-family homes (as opposed to inner city apartments), and new optimism about the future. The boom peaked around 1957 and then began to fade. A period of high inflation, interest rates, and unemployment after 1973 weakened confidence in fiscal policy as a tool for regulating the overall pace of economic activity. The U.S. economy grew by an average of 3.8% from 1946 to 1973, while real median household income surged by 74% (or 2.1% a year). The worst recession in recent decades, in terms of lost output, occurred during the financial crisis of 2007–2008, when GDP fell by 5.0% from the spring of 2008 to the spring of 2009. Other significant recessions took place in 1957–1958, when GDP fell 3.7% following the 1973 oil crisis, with a 3.1% fall from late 1973 to early 1975, and in the 1981–1982 recession, when GDP dropped by 2.9%. Recent, mild recessions have included the 1990–1991 downturn, when output fell by 1.3%, and the 2001 recession, in which GDP slid by 0.3%; the 2001 downturn lasted just eight months. The most vigorous, sustained periods of growth, on the other hand, took place from early 1961 to mid-1969, with an expansion of 53% (5.1% a year), from