Thanks to jill/text I discoverd The Progress and Freedom Foundation’s Digital Economy Factbook, Ninth Ed. (PDF) on their Issues & Publications page. The Factbook is full of facts and graphs for everything from Internet hosts to spam. From the PFF blog I also found a compilation of media metrics charts on Flickr like this one of Information Creation and Available Storage:
As jill/text (where I read about this) reminds us, we have to be careful with this Factbook – it is put out by an industry advocacy group with a lot of powerful sponsors from Google to AT&T. They have an agenda to advocate for protection of digital content.