2. The method of claim 1 , further comprising, for a particular related search query from the one or more related search queries, normalizing the weighted click data for the document and the particular related search query by dividing the weighted click data for the document and the particular related search query by a number of times the related search query was received over the period of time; wherein combining the weighted click data comprises combining normalized weighted click data for the document and the one or more related search queries.
2. The method of claim 1 , further comprising, for a particular related search query from the one or more related search queries, normalizing the weighted click data for the document and the particular related search query by dividing the weighted click data for the document and the particular related search query by a number of times the related search query was received over the period of time; wherein combining the weighted click data comprises combining normalized weighted click data for the document and the one or more related search queries. 3. The method of claim 2 , wherein combining the normalized weighted click data comprises adding together the normalized weighted click data for the document and the one or more related search queries.