1. A method performed by one or more devices, the method comprising: determining, by at least one of the one or more devices, a frequency at which a document is selected over time when the document is included in a set of search results, where determining the frequency at which the document is selected includes: determining a first rate at which the document is selected in a first time period, determining a second rate at which the document is selected in a second time period, and comparing the first rate and the second rate to determine whether there is an increase or a decrease in the rate at which the document is selected between the first and second time periods; generating, by at least one of the one or more devices, a score for the document based on the frequency at which the document is selected over time when the document is included in a set of search results, where generating the score for the document includes: scoring the document based on whether there is an increase or a decrease in the rate at which the document is selected; and ranking, by at least one of the one or more devices, the document with regard to at least one other document based on the score.