Percentage of high school graduates enrolling in college and percentage of college graduates pursuing postgraduate degrees: Digest of Education Statistics, National Center for Education Statistics, U.S. Department of Education.
Total number of patents granted in 1980 and 2012: U.S. Patent Statistics Report, U.S. Patent and Trademark Office.
U.S. venture capital funds by year: Dow Jones Financial Information Services; Thomson Reuters; National Venture Capital Association.
Length of high-speed rail track by country: International Union of Railways.