http://www.prb.org/Publications/Datasheets/2012/world-population-data-sheet/fact-sheet-us-population.aspx http://www.prb.org/Publications/Datasheets/2012/world-

http://www.prb.org/Publications/Datasheets/2012/world-population-data-sheet/fact-sheet-us-population.aspx http://www.prb.org/Publications/Datasheets/2012/world-popula...