units. The current faculty includes 262 American Academy of Arts and Sciences Fellows, three Fields Medalists, 77 Fulbright Scholars, 139 Guggenheim Fellows, 90 members of the National Academy of Engineering, 144 members of the National Academy of Sciences, ten Nobel Prize winners, four Pulitzer Prize winners, 125 Sloan Fellows, 8 Wolf Prize winners and 1 Pritzker Prize winner. Library system Berkeley's 32 libraries together contain more than 13 million volumes and cover over 12 acres (4.9 ha) of land, forming one of the largest library complexes in the world. Doe Library serves as the library system's reference, periodical, and administrative center, while most of the main collections reside in the subterranean Gardner Main Stacks and Moffitt Undergraduate Library. The Bancroft Library, which has over 400,000 printed volumes and 70 million manuscripts, pictures, and maps, maintains special collections that document the history of the western part of North America, with an emphasis on California, Mexico and Central America. The Bancroft Library also houses the Mark Twain Papers, the Oral History Center, the Center for the Tebtunis Papyri and the University Archives. Rankings National The 2018–19 Center for World University Rankings (CWUR) ranked the university the top public university in the nation and 4th overall based on quality of education, alumni employment, quality of faculty, publications, influence, and citations. In 2014, The Daily Beast Best Colleges report ranked Berkeley 11th in the country. For 2015 Kiplinger ranked Berkeley the 4th best-value public university in the nation for in-state students, and 6th for out-of-state students. The Money Magazine Best Colleges ranking for 2015 ranked Berkeley 9th in the United States, based on educational quality, affordability and alumni earnings. For 2021, QS "World University Rankings: USA" placed Berkeley 4th among all US universities and 1st among publics. The 2013 Top American Research Universities report by the Center for Measuring University Performance ranked Berkeley 8th overall, 5th in resources, faculty, and education, 9th in resources and education, and 1st in education. In the 2022-2023 U.S. News & World Report national university rankings, Berkeley was the top public school and 20th overall. Washington Monthly ranked Berkeley 9th among national universities in 2022, with criteria based on research, community service, and social mobility. Global For 2020–21, the Center for World University Rankings (CWUR) ranked the university 12th in the world based on quality of education, alumni employment, quality of faculty, and research performance. In 2017, the Nature