http://www.bigpictureagriculture.com/2013/03/weve-lost-9-7-million-acres-of-crp-land-in-five-years-334.html
Check out the graph/map in the link and it answers your question.
And regarding the current low price per bushel: to me this appears to be the result of supply and demand. Too many have tried to cash in on a the ethanol subsidy, less gas is being used, and I hope more consumers are avoiding ethanol at all costs if they possibly can.