National scientific performance evolution patterns: Retrenchment, successful expansion, or overextension

National governments would like to preside over an expanding and increasingly high‐impact science system but are these two goals largely independent or closely linked? This article investigates the relationship between changes in the share of the world's scientific output and changes in relative citation impact for 2.6 million articles from 26 fields in the 25 countries with the most Scopus‐indexed journal articles from 1996 to 2015. There is a negative correlation between expansion and relative citation impact, but their relationship varies. China, Spain, Australia, and Poland were successful overall across the 26 fields, expanding both their share of the world's output and its relative citation impact, whereas Japan, France, Sweden, and Israel had decreased shares and relative citation impact. In contrast, the USA, UK, Germany, Italy, Russia, The Netherlands, Switzerland, Finland, and Denmark all enjoyed increased relative citation impact despite a declining share of publications. Finally, India, South Korea, Brazil, Taiwan, and Turkey all experienced sustained expansion but a recent fall in relative citation impact. These results may partly reflect changes in the coverage of Scopus and the selection of fields.