(a) A heat map indicating the number of preprints per country, based on the institutional affiliation of the senior author. The color coding uses a log scale. (b) The total preprints attributed to the seven most prolific countries. The x-axis indicates total preprints listing a senior author from a country; the y-axis indicates the country. The ‘Other’ category includes preprints from all countries not listed in the plot. (c) Similar to panel b, but showing the total preprints listing at least one author from the country in any position, not just the senior position. (d) Proportion of total senior-author preprints from each country (y-axis) over time (x-axis), starting in November 2013 and continuing through December 2019. Each colored segment indicates the proportion of total preprints attributed to a single country (using same color scheme as panels (b and c), as of the end of the month indicated on the x-axis.