All we need to understand that factoid is some basic demographic knowledge. The population of the United States was estimated at 329 million in July 2018.
0-14 years: 18.62 percent
15-24 years: 13.12 percent
25-54 years: 39.29 percent
55-64 years: 12.94 percent
65 years and over: 16.03 percent
Next, we must think about other groups who have had limited wealth-building opportunities.