4. The method of claim 1 , where the score is a first score, the method further comprising: determining a frequency at which the document is selected over time when the document is included in a set of search results; generating a second 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; and ranking the document with regard to at least one other document based on the second score.
5. The method of claim 4 , where determining the frequency at which the document is selected includes: determining the frequency at which the document is selected over time based on behavior of a single user.