17. The system of claim 12 , wherein the operations further comprise: determining a query value Q for the query, the query value being based on the QtoA ratio; determining a resource value D for the resource, the resource value being based on a function of an age of the resource, F(age), wherein age is the age of the resource; and calculating S′ as a product of S and a value of a boosting function of the query value Q and the resource value D.
17. The system of claim 12 , wherein the operations further comprise: determining a query value Q for the query, the query value being based on the QtoA ratio; determining a resource value D for the resource, the resource value being based on a function of an age of the resource, F(age), wherein age is the age of the resource; and calculating S′ as a product of S and a value of a boosting function of the query value Q and the resource value D. 18. The system of claim 17 , wherein the boosting function is a continuous function having a range of values that includes values less than 1, a value equal to 1, and values greater than 1, whereby the product of S and the value of the boosting function can be less than S, equal to S, or greater than S.