Kudos to the analysts at SCImago. They have provided an outstanding, entertaining and educational perspective on worldwide academic publishing. I'll focus here on only one aspect: citations. Although the United States is the leader in citations at 87M citations, it is a surprising laggard in self-citation (32% citations are self-citations). The leaders are China (62%), Lithuania (38%), and Iran (37%). However, in the domain of medicine, authors in the United States are considerably less reticent and rack up a self-citation rate of 47%, earning them second place. The map below of the subject areas of the USA publications indicates where the action is.
Hat tip: Peter Park