18. The system of claim 17 , where the one or more server devices is further to: determine a first number of documents, in the set of second documents, that currently contain a link to the first document; determine a second number of documents, in the set of second documents, that previously contained a link to the first document; and assign the freshness score based on the first and second numbers.
18. The system of claim 17 , where the one or more server devices is further to: determine a first number of documents, in the set of second documents, that currently contain a link to the first document; determine a second number of documents, in the set of second documents, that previously contained a link to the first document; and assign the freshness score based on the first and second numbers. 19. The system of claim 18 , where the one or more server devices is further to: assign a first freshness score to the first document when the first number of documents is greater than the second number of documents; and assign a second freshness score to the first document when the first number of documents is not greater than the second number of documents, where the first freshness score is greater than the second freshness score.