Yale is organized into fourteen constituent schools: the original undergraduate college, the Yale Graduate School of Arts and Sciences, and twelve professional schools. While the university is governed by the Yale Corporation, each school's faculty oversees its curriculum and degree programs. In addition to a central campus in downtown New Haven, the University owns athletic facilities in western New Haven, including the Yale Bowl, a campus in West Haven, Connecticut, and forest and nature preserves throughout New England. The university's assets include an endowment valued at $25.6 billion as of September 2015, the second largest of any educational institution.The Yale University Library, serving all constituent schools, holds more than 15 million volumes and is the third-largest academic library in the United States.

How many schools is Yale composed of?