From 1870 to 1970, the percent of American workers based on farms fell by 90 percent, and then again from 1950 to 2010, the percent of Americans working in factories fell by 75 percent.
De 1870 a 1970, a percentagem de trabalhadores agrícolas nos EUA desceu em 90%, e outra vez de 1950 a 2010, a percentagem de trabalhadores fabris norte-americanos desceu em 75%.