15. A system, comprising: a computing device that is configured to: receive a search query; identify one or more listings responsive to the search query; determine, for each of the one or more listings, a relevancy score based on one or more parameters in the search query, an expected click through rate, and a content density boost for a listing category that is a ratio of a click-through rate when a particular type of field is included in a listing in the listing category to a click-through rate when the particular type of field is excluded from a listing in the listing category; and calculate, for each of the one or more listings, a performance score based at least in part on the relevancy score, the expected click through rate, and the content density boost.
20. The system of claim 15 , the computing device further configured to adjust the content density boost based on at least one of the one or more parameters in the search query.