The series comes from the 'Current Population Survey (Household Survey)'
The source code is: LNU01327660
Source: US. Bureau of Labor Statistics
Release: Employment Situation
US. Bureau of Labor Statistics, Civilian Labor Force Participation Rate: High School Graduates, No College, 25 years and over [LNU01327660], retrieved from FRED, Federal Reserve Bank of St. Louis https://research.stlouisfed.org/fred2/series/LNU01327660/, July 2, 2015.