Source: U.S. Bureau of Labor Statistics
Release: U.S. Import and Export Price Indexes
For more information, please see the Import/Export Price Indexes web site at http://www.bls.gov/mxp
U.S. Bureau of Labor Statistics, Import Price Index (Harmonized System): Optical, photographic, measuring and medical instruments [IP90], retrieved from FRED, Federal Reserve Bank of St. Louis; https://fred.stlouisfed.org/series/IP90, May 25, 2018.