Google is your friend: http://www.northwestern.edu/newscenter/stories/2013/05/lets-hear-it-for-the-class-of-2017.html
“By standard academic measures, the Class of 2017 is the strongest in Northwestern’s history. Ninety-one percent of incoming freshmen ranked in the top 10 percent of their high school class, and the so-called “middle 50 percent” SAT score is 1390 to 1550 (meaning one-half of the class scored within this range, while one-quarter scored below and above the range, respectively).”