For nearly a half century wealthy nations young populations have been declining versus rising young among poor nations...offset by secularly declining interest rates and the addition of over $240 trillion in global debt to maintain unnaturally high rates of economic growth.  The consumer nations population of relatively wealthy young has been declining for nearly 4 and a half decades, falling over 100 million or 12% during that span.  The population of relatively poorer nations young has increased by nearly 190% or increased by 570 million.  On average, each wealthier nations young person represents $26.5k in per capita consumption versus each poor nations young represents $1.5k in per capita consumption. 

Said otherwise, it takes 15 more poor nations inhabitants to replace the loss of every one wealthier nations inhabitant to simply maintain flat consumption, thus the impetus for interest rate cuts and massive increases in debt among the wealthy.  Obviously, consumption hasn't been flat but has grown tremendously, primarily thanks to interest rate cuts, cheap debt, and only in a very small part from growth in consumption among the poorer nations population gains.