Agricultural Prices 2006 Summary, July 20, 2007 (239 pages, PDF): "The 47th Annual Summary of Agricultural Prices contains prices farmers received for commodities sold as well as prices paid for production input goods and services. Prices are weighted and aggregated into price indexes. These indexes provide measures of relative price changes for agricultural outputs and inputs. The State, Regional, and U.S. average prices for agricultural commodities and farm production inputs are based on voluntary reports from agri-business firms, merchants, dealers, and farmers throughout the Nation. These data are collected at regular intervals using mailed inquiries, telephone, and personal enumeration."