I don't have a source, nor do I fully believe the original poster, but do consider: 7x population growth, shift from 80% rural to 90% urban. Where "rural" is l

I don't have a source, nor do I fully believe the original poster, but do consider: 7x population growth, shift from 80% rural to 90% urban. Where "rural" is low economic engagement and "urban" is a job-holder. shift from single-earning families to dual-earner, where again a stay-at-home mom does not increase the size of the economy while a working one does (and please, I know this is unfair and the tremendous value a full time Mom provides). Multiple these three shifts and you get a pretty big increase in the economy, with zero increase in productivity.