1. A computer-implemented method for evaluating the supply of electronic content on an electronic network, the method comprising: receiving search results history for a plurality of queries; determining a variability of the search results history for queries for at least one keyword; determining a supply value indicative of a supply of electronic content on the electronic network relating to the at least one keyword, based on the determined search results variability; and requesting, over the electronic network, electronic content relating to the at least one keyword based on the determined supply value.