How much of Stanford's class was admitted by Early Action?

When the adcom makes its early decisions, do they have a certain amount they accept so they can save a decent percentage for regular decision? And if so, what is that amount?

Seems to be about 30% (for context, the total number admitted was about 2150 people): http://news.stanford.edu/2015/12/11/early-admit-announce-121115/

Obviously there isn’t a strict number, but the proportion is roughly constant over the years.