The series comes from the 'Current Population Survey (Household Survey)'
The source code is: LNU02300025
Source: US. Bureau of Labor Statistics
Release: Employment Situation
US. Bureau of Labor Statistics, Employment-Population Ratio: 20 years and over, Men [LNU02300025], retrieved from FRED, Federal Reserve Bank of St. Louis https://research.stlouisfed.org/fred2/series/LNU02300025/, July 2, 2015.