Young adults in the United States are being squeezed out of the labor force as older workers either delay retirement or seek jobs to rebuild nest eggs destroyed by the recession, a study showed on Wednesday. The size of the labor force fell 6.3 percent for young workers, but increased 8.5 percent for workers 55 years and older between December 2007 and January 2010, according to the study by the Washington-based Economic Policy Institute (EPI).