June 2010 . . . . . 339 Billion/day average
December 2010 . . 92 Billion/day average
December 2009 .
So comparing December with the 2010 peak, or comparing December year to year, there is a huge decrease in the last quarter on 2010.
The steady decline from September to December is most likely attributable to the exposure of Igor Gusev in the Russian media, Russian police action in seizing his computers, and the immediate shut-down of his GlavMed affiliate program that was funding the spammers and providing the pharmacy fraud and fake watch scams.