Journal Citation Reports (JCR) now has 10 years of journal metrics available:

Journal Citation Reports  (1999+)  (Science & Social Science Editions.)

From Information services provider Thomson Reuters, US, "JCR claims to be the most widely used tool for assessing the world’s leading journals. The metrics it offers, including Journal Impact Factor, empower users to objectively evaluate a journal’s performance and its influence on research globally."  JCR ranks 9100 journals from 2200 publishers in 78 countries.

Source:  Knowledgespeak Newsletter, June 18, 2010