The series comes from the 'Current Population Survey (Household Survey)'
The source code is: LNU04028615
Source: US. Bureau of Labor Statistics
Release: Employment Situation
US. Bureau of Labor Statistics, Unemployment Rate: All Industries Government Wage and Salary Workers [LNU04028615], retrieved from FRED, Federal Reserve Bank of St. Louis https://research.stlouisfed.org/fred2/series/LNU04028615/, July 29, 2015.