Stumbled upon this. Its a bit dated (from early this year).

http://www.care2.com/greenliving/mea...declining.html

Per person meat, poultry and fish consumption reached its maximum in 2004 at 237.5 pounds, and is now down to 224 pounds. (They say 2004 was the peak year in popularity for high protein diets such as Atkins.)
Doesn't seem like too much to me (i assume its per year), but i guess 13.5 pounds adds up across the whole nation. I will think of it as a bit of good news, and hope that the trend keeps decreasing not increasing.

Here is what the author conjectures as to why:

One reason for the meat consumption decline is increasing grain prices, and they implicate government support for biofuels, which probably means ethanol. Corn grown for ethanol is used to feed livestock sometimes, but it typically is not used to feed people, as is commonly held, so growing it does not take food away from humans. Is is it truly biofuels that are making grain prices higher and reducing meat consumption?
Probably not as much as the global recession that affected many countries around the world. Also awareness of climate change – a global problem that is altering weather and habitats for wild animals and plants – must be changing attitudes.
Several other environmental devastations of meat eating are written about. Nothing about ethics, which is annoying... taking it out of the debate seems to me as if animals are still seen by many as cartesian machines of production that happen to be inefficient, basically phrasing it only in human terms.

Either way, it is possible that ethics are also a part of the decline too.