Economic output fell at its fastest pace on record last spring as the coronavirus pandemic forced businesses across the United States to close their doors and kept millions of Americans shut in their homes for weeks. Gross domestic product — the broadest measure of goods and services produced — fell 9.5 percent in the second quarter of the year, the Commerce Department said Thursday. On an annualized basis, the standard way of reporting quarterly economic data, G.D.P. fell at a rate of 32.9 percent. …The only possible comparisons in modern American history came during the Great Depression and the demobilization after World War II.