QS Quacquarelli Symonds released the 21st edition of the QS World University Rankings, the only ranking system to measure both employability and sustainability performance. For the thirteenth consecutive year, MIT leads the table, though two-thirds of the United States' ranked universities have dropped in the last year. Imperial College London jumps four places to rank 2nd; the University of Oxford and Harvard University remain 3rd and 4th respectively; the University of Cambridge rounds out the top five. Caltech is the only institution to break into the top 10.