Fewer low-skilled immigrants in those countries compared to the US, is the usual explanation given. The Economist loves to talk about this topic. One recent ex

Fewer low-skilled immigrants in those countries compared to the US, is the usual explanation given. The Economist loves to talk about this topic. One recent example: https://www.economist.com/graphic-detail/2017/08/30/immigrants-boost-americas-birth-rate https://www.economist.com/graphic-detail/2017/08/30/immigran...