Eigenfactors are calculated for those journals that are covered by Thomson Reuters' Journal Citation Reports and can be found in that database. Eigenfactors are calculated for some other journals as well and can be found in other places.
One of the benefits of Eigenfactors is that they are free to access so no subscription is needed to find or use the numbers. Go to http://www.eigenfactor.org to find the scores for journals - both those in the Journal Citation Reports and those that are not in that collection but have eigenfactors.
You can search for individual journals or search by ISI categories (the categories used in Thomson Reurters' Journal Citation Reports), or look at all of them by year.