1. The accompanying table shows data from the World Bank, World Development Indicators, for real GDP per capita in 2010 U.S. dollars for Argentina, Ghana, South Korea, and the United States for 1960, 1980, 2000, and 2015. Argentina Ghana South Korea United States Percentage of Percentage of Percentage of Percentage of 1960 2015 Real 1960 2015 Real 1960 2015 Real 1960 2015 Real GDP real real GDP per real real GDP per real real GDP per real real per capita GDP GDP capita GDP GDP capita GDP GDP capita GDP GDP (2010 per per (2010 per per (2010 per per (2010 per per Year dollars) capita capita dollars) capita capita dollars) capita capita dollars) capita capita 1960 $5,853 ? $1,053 ? ? $1,103 ? $17,037 ? ? 1980 8,408 ? 901 ? 3,911 28,734 ? ? 2000 8,544 ? 975 ? 15,105 45,056 2015 12,128 ? ? 1,696 ? ? 25,023 ? ? 51,486 ? a. Complete the table by expressing each year's real GDP per capita as a percent- age of its 1960 and 2015 levels. b. How does the growth in living standards from 1960 to 2015 compare across these four nations? What might account for these differences