Milk Compared to (Sugar, Corn, Wheat)

The price of milk (all scaled to 100%)... relative to Wheat, Corn, and Sugar

From January of 2009 to June of 2014 the price of milk in general went up... however in the last 5 years has been going down?

Details:
Commodity Main Exchange Contract Size Symbol
Wheat CBOT 5000 bu W/ZW (Electronic)
Corn CBOT 5000 bu C/ZC (Electronic)
Sugar No.11 ICE 112,000 lb SB