If you’re like us, you’ve been racking your memory to figure out just when it was that Christie’s started pulling out of the two horse race for Contemporary art and began to dominate the category on its own. To answer that question, Karolina Prawdzik put together these charts of New York’s evening sales. They show pretty clearly that November of 2012—just two years ago—was the last time the two auction houses were running neck and neck.

What the chart makes clear is that Sotheby’s has not done poorly at all in the category. They’ve maintained their sales totals and kept the average price at a very respectable $6m or so. Contrary to what Daniel Loeb has suggested, Sotheby’s hasn’t declined. Christie’s has kicked in the afterburners. But how? What’s the secret sauce of Christie’s increased sales in 2013 and 2014? A greater number of specialists? Better contacts and relationships? More generous guaranteees?