In 2003, central and local governments in China supported 1,552 institutions of higher learning (colleges and universities), along with their 725,000 professors and 11 million students (see List of universities in China). There are over 100 National Key Universities in the Project 211, including Peking University and Tsinghua University, which are considered to be part of an elite group of Chinese universities. Chinese investment in research and development has grown by 20 percent per year since 1999, exceeding $100 billion in 2011. As many as 1.5 million science and engineering students graduated from Chinese universities in 2006. By 2008, China had published 184,080 papers in recognized international journals—a seven-fold increase from 1996. In 2017, China surpassed the U.S. with the highest number of scientific publications.