The Commerce Department.

The closest thing I could find to a source would be this, but the industries aren't split into 'content'

   http://www.bea.gov/iTable/iTable.cfm?ReqID=5&step=1

According to this, the "Information" industry is about $225B and "Computer Systems Design" is $198B.

Entertainment & Media was the bracket I pulled from, but the content industry is larger than that, as was pointed out elsewhere on the thread.

Is there, like, a link?