Determine the productivity level of US

Those who live in relatively poor regions of the world today have higher material living standards than their predecessors who lived in those regions a century ago. However the relative gap regarding the industrial core has grown extravagantly and extraordinarily. In the first half of 19th century the average inhabitant of an average country had perhaps one-half the material standard of living of a citizen of the world's leading industrial edge economy. Today average inhabitant of an average country has just one-sixth the productivity level and material standard of living of the leading edge.