Dr. Grabow was making 250,000-300,000 briars a year when it was spun off and sold in 2006. They must easily be the largest single-brand producer in the world. I can easily believe that the biggest four or five operations--Pete, Sav, Stan, Dr. G, and all the brands made in St. Claude--crank out 600,000 pipes a year.
That remaining 400,000, I'm not as sure. Might be close to a mil, though.