Mark Bittman credits [NYT] a recent, significant fall in meat consumption to changing attitudes:
Some are choosing to eat less meat for all the right reasons. The Values Institute at DGWB Advertising and Communications just named the rise of "flexitarianism" — an eating style that reduces the amount of meat without "going vegetarian" — as one of its top five consumer health trends for 2012. In an Allrecipes.com survey of 1,400 members, more than one-third of home cooks said they ate less meat in 2011 than in 2010. Back in June, a survey found that 50 percent of American adults said they were aware of the Meatless Monday campaign, with 27 percent of those aware reporting that they were actively reducing their meat consumption.
Chart via Brad Plumer, who highlights an economic explanation:
The Daily Livestock Report blames rising meat prices in the United States. As countries like China and India get richer, they’re eating more meat, which is helping to drive up U.S. exports and making beef, pork, and chicken more expensive here at home. Ethanol also plays a role: Nowadays, American farmers divert bushels and bushels of corn to make fuel, which drives up feed prices and, again, makes meat pricier.