The series comes from the 'Current Population Survey (Household Survey)'
The source code is: LNS13000024
Source: US. Bureau of Labor Statistics
Release: Employment Situation
US. Bureau of Labor Statistics, Unemployment Level - 20 years and over [LNS13000024], retrieved from FRED, Federal Reserve Bank of St. Louis https://research.stlouisfed.org/fred2/series/LNS13000024/, June 2, 2015.