If we just isolate the annual change in the 0 to 55 year global population (minus Africa...explained HERE), we see annual population growth has decelerated by 77% or we are adding 49 million fewer 0 to 55yr/olds annually than we did during peak growth in 1988. Within a decade, the world under 55yr/old population (excluding Africa) will cease growing and begin an unknown period of depopulation. In fact, the forward estimates are based on the UN's more "optimistic" medium variant...the reality will almost certainly be lower. Meanwhile, annual global GDP growth in dollar terms has been wildly gyrating from record growth to unprecedented record declines (chart below).
And a best guess where this is going...Declining population of potential child bearing population, declining potential # of new home buyers, car buyers, tax payers, employees...and debt blowing through the roof and deeply negative interest rate policy in effect.
The Fed and like central banks of the world want economies to grow at rates far beyond what organic growth supports. The further the central banks intervene to force populations whose growth is decelerating (and resultant potential economic growth) to overshoot, the longer the duration and severity of the resultant ultimate rebalancing. One of the great many flaws of modern day, central bank driven economics is the idea that economic growth is all about increasing capacity or production. Simply put, it doesn't matter how many widgets or how efficiently you can make them if there is a decelerating growth and soon an outright declining quantity of potential buyers on the other end.