The portion of funds of funds that come from the federal government is smaller than you think, and conservatives are constantly posturing to take even that away. (Recall the Big Bird meme that came out of the presidential debates?). The lions share of federal funds go to keeping stations broadcasting, not towards content creation.

It's unlikely that any given piece of content was wholly funded by the public.

http://www.publicdomainsherpa.com/us-government-works.html

http://en.wikipedia.org/wiki/Corporation_for_Public_Broadcas...