https://www.weforum.org/stories/2016/05/this-demographic-shift-is-shaping-the-us-economy/
The proportion of unmarried American women is on the increase, and this could change the economy.
demographic shiftus economyshapingworldeconomic
https://www.fool.com/retirement/2018/09/10/this-8-decade-long-demographic-shift-is-crippling.aspx
Adjusting this aspect of Social Security just once since the program's inception has led to big problems.
demographic shiftsocial securitydecadelong