What is this?

The Producer Price Index measures the average change over time in the selling prices received by domestic producers of goods and services from the perspective of the seller. This chart displays the Producer Price Index for HVAC and commercial refrigeration equipment (series 3334)

(definition and chart data obtained from http://www.bls.gov/ppi/)

Weekly Gas Prices

How do I use this?

Use the PPI as a possible indicator of price movements from your suppliers/distributors.