I never said anything about percent of food, my comment was based on type of food. We have huge subsidies for some types of food. That does not mean ex: pot growers get a large subsidy. It's really a fairly narrow group of foods which get the vast majority of subsidies and are then produced in truly mind boggling quantities.
There was a great corn documentary a while ago where a small processor kept making larger larger grain silo's for a while as productivity increased. Until, they simply gave up they now just have a huge pile with a tarp over it. http://www.imdb.com/title/tt1112115/
Which is why corn sirup is in just about everything. Also, avacadoes for example had an indirect subsidy in the name of avoiding pests in imported Mexican avacadoes. Still, the unequal subsides on various food products causes all sorts of problems as substitutions are generally of a lower quality in some way. Arguably much if the obesity epidemic directly relates to subsidizing calorie dense foods instead of fruits and vegetables.