United States: Real GDP per Working-Age Person 8.499 9.499 10.499 11.499 12.499 1900 1910 1920 1930 1940 1950 1960 1970 1980 1990 2000 year index(1900=100) 100 200 400 800 50           31?:?> :/< :/<=98 .?<381 >2/  /: