Source: US. Bureau of Labor Statistics
Release: Consumer Price Index
US. Bureau of Labor Statistics, Consumer Price Index for All Urban Consumers: Utility (piped) gas service in West - Size Class a (over 1,500,000 persons) [CUURA400SEHF02], retrieved from FRED, Federal Reserve Bank of St. Louis; https://fred.stlouisfed.org/series/CUURA400SEHF02, December 4, 2016.