Here is the data from the US State Department showing the changing composition of source countries involved in significant numbers of international adoptions to the United States. This information now goes back to fiscal year 1985, which is the earliest year for which I have been able to obtain statistics.
A few words about this graphic. This clearly shows that until a few years ago Korea was, by far, the predominant source of international adoptions to the US. Currently, there is a split between China, Russia and Korea, with adoptions from Latin America holding roughly constant. Adoptions from Romania and Vietnam are increasing. Adoptions from India (not plotted) are also significant and have held steady for a number of years. Note that in FY91, for only one year, Romanian adoptions dominate the distribution.
The main point of this graphic, of course, is to show how adoption from China has grown from almost zero, to the largest single country of origin in FY95, with 2130 children and a further increase to 3333 in FY96. Current adoption rates suggest that the number could top 4,000 in FY97.