Ranking documents based on a series of web graphs collected over time is provided. A ranking system provides multiple transition probability distributions representing different snapshots or times. Each transition probability distribution represents a probability of transitioning from one document to another document within a collection of documents using a link of the document. The ranking system determines a stationary probability distribution for each snapshot based on the transition probability distributions for that snapshot and the stationary probability distribution of the previous snapshot. The stationary probability distributions represent a ranking of the documents over time.