Grens K. 2006. NSF examines plateau in US publications. US scientists’ share of publications is declining in the face of competition from countries like China. The Scientist, November 14.

The Science Resources Statistics Division of the National Science Foundation held a workshop to explore why the number of US science publications remained essentially flat from 1992 to 2002, leading to a drop in the US share of publications from 38% to 30%.
One of the reason is that the percentage of US publications is declining as other countries increase their output. Moreover, this is partly due to an increase in global collaborations and to a growing appreciation among non-US researchers for the value of publishing in English-language journals, making it more competitive for American scientists to get their work accepted.
Much of the new competition appears to be coming from China.