Source: US. Bureau of Labor Statistics
Release: Employment Situation
The civilian labor force is the sum of employed and unemployed persons.
The series comes from the 'Current Population Survey (Household Survey)'.
US. Bureau of Labor Statistics, Civilian Labor Force - College Graduates - Doctoral Degree, 16 years and over [CGDDL16O], retrieved from FRED, Federal Reserve Bank of St. Louis; https://fred.stlouisfed.org/series/CGDDL16O, August 26, 2016.