Four of these series are published by the U.S. Bureau of Economic Analysis and used to construct the two spliced data series produced by the Federal Reserve Bank of St. Louis. The historical section of the spliced data series (January 1967 to December 1996) is calculated by using the Standard Industrial Classification System (SIC) of Real Manufacturing and Trade Industries Sales, while the section after December 1996 uses to the North American Industry Classification System (NAICS). The Real Manufacturing and Trade Industries Sales data are used by the NBER to gauge the business cycles of the U.S. economy.