Source: US. Bureau of Labor Statistics
Release: Employment Situation
The series comes from the 'Current Population Survey (Household Survey)'
The source code is: LNU03032224
US. Bureau of Labor Statistics, Unemployment Level: Construction and Extraction Occupations [LNU03032224], retrieved from FRED, Federal Reserve Bank of St. Louis; https://fred.stlouisfed.org/series/LNU03032224, July 23, 2016.