It's an article from January of this year.

Podcasts are becoming a bigger part of Americans' media diets - they may be starting to cut into the consumption of media staples like AM/FM radio. “This is, indeed, going to be a big year for podcasting,” Edison Vice President Tom Webster wrote in a blog post outlining the findings. “This is but our first clue.”
http://www.ibtimes.com/americans-lis..._plusone_share