From 1950 to 2004, the total U.S. resident population grew from 150 million to 294 million--an annual growth rate of 1%. During that same time, the 65 and older population grew twice as rapidly--increasing from 12 million to 36 million. The 75 and older population grew close to 3% faster than the total population, increasing from 4 million to 18 million.
Centers for Disease Control and Prevention, National Center for Health Statistics. 2005. 'Health, United States, 2005: With chartbook on trends in the health of Americans'.