The number of higher education institutions, teachers/researchers and publications from the U.S., China, and the U.K. during the period 1980–2018.

(a) Institutions; (b) teachers/researchers; (c) publications (from Scopus as at 1 January 2020). [Notes: The U.S. Department of Education provided biannual data after 1986. No data were available from the National Bureau of Statistics of China for the period 1981–1984 and from the U.K. Higher Education Statistics Agency for the period 1980–1995.]