The U.S. Census Bureau maintained time series of monthly sales and end-of-month inventory estimates of retailers based on the Standard Industrial Classification (SIC) system. The SIC-based time series were discontinued as the North American Industry Classification System (NAICS) time series were newly introduced.
Source: US. Bureau of the Census
US. Bureau of the Census, Retail Sales (DISCONTINUED) [RETAIL], retrieved from FRED, Federal Reserve Bank of St. Louis https://research.stlouisfed.org/fred2/series/RETAIL, May 31, 2016.