In 1940, the percentage of children who earned more than their parents by age 30 was 92%. The percentage fell to 80% by 1950, and from 1960-1975 it held at 60%. It’s since continued to fall and is now 50%. There are several reasons for the decline. GDP growth has slowed as our economy has matured and become big. Also, income growth has been strongest for those with high salaries.