The change in nations Core populations (25-54yr/olds) have driven economic activity for the later half of the 20th century, first upward and now downward. The Core is the working population, the family forming population, the child bearing population, the first home buying, and the credit happy primary consumer. Even a small increase (or contraction) in their quantity drives economic activity magnitudes beyond what the numbers would indicate.
To highlight the linkage of Core populations to economic activity, the chart below shows the European 25-54yr/old population vs. the best indicator of economic activity, total energy consumption (data available starting from 1980). The implications are pretty straightforward. European economic activity (& resultant energy consumption) will contract for decades, at a minimum, with the declining Core population. The pie is shrinking and now it's simply a fight for who gets bigger slices.
Given this, consider Germany was well aware of it's post WWII collapsing birth rate and the impact of this on economic growth as this shrinking population of young made it's way into the Core. Consider Germany's Core population peaked in 1995 and it's domestic consumer base has been shrinking since, now down over 3.3 million potential consumers (about a 9% Core decline...remember a depression is a 10% decline in economic activity, which a 9% and growing decline in German consumers would have almost surely induced).
The chart below shows Germany's Core population from 1950-->2040...but understand this is no guestimate through 2040. This is simply taking the existing 0-24yr/old population (plus anticipated immigration) and sliding them into the Core through 2040. Germany's Core population is set to fall by over 30% or 10+ million by 2040 (far more than the 7 million Germans of all ages who died in WWII).
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