X-ray constraints on the fraction of obscured active galactic nuclei at high accretion luminosities

THALES - European Union [383549]; Greek Government of the programme 'Education and lifelong learning'; FONDECYT Postdoctorados [3160439]; Ministry of Economy, Development, and Tourism's Millennium Science Initiative [IC120009]; Millennium Institute of Astro-physics MAS; Alfred P. Sloan Foundation; National Science Foundation; U.S. Department of Energy Office of Science; University of Arizona; Brazilian Participation Group; Brookhaven National Laboratory; Carnegie Mellon University; University of Florida; French Participation Group; German Participation Group; Harvard University; Instituto de Astrofisica de Canarias; Michigan State/Notre Dame/JINA Participation Group; Johns Hopkins University; Lawrence Berkeley National Laboratory; Max Planck Institute for Astrophysics; Max Planck Institute for Extraterrestrial Physics; New Mexico State University; New York University; Ohio State University; Pennsylvania State University; University of Portsmouth; Princeton University; Spanish Participation Group; University of Tokyo; University of Utah; Vanderbilt University; University of Virginia; University of Washington; Yale University