"So for example, if you look at the U.S., productivity growth mid-century or say between, you know, 1920, 1970, was maybe about 1.9% a year. Now most economists think it’s much lower, maybe around sort of .4% a year, something like that."

Isn't this just because the US was riding off of the coattails of two world wars and being _the_ global superpower? I wonder what the data says about the rest of the world in that period, probably not so good?