Commodity prices have been heading downwards in recent months - with oil,sugar,aluminum and copper all well below their peaks. But cocoa has bucked the trend - apparently confirming the popular belief that people turn to chocolate during an economic downturn.Cocoa grows best in equatorial regions - which produce about 3.5 million tonnes of beans per year. The island nation of Sao Tomé and Principe off the west African coast lives almost exclusively from cocoa exports. Production levels fell sharply in the mid-1990s but have since recovered. Today some 1400 farmers grow organic cocoa on the islands - a product that fetches a premium price in Europe.