Via the World Bank, the graphic above shows "brain circulation" -- the immigration and emigration of researchers -- for 16 countries in 2011. Countries that experienced a "drain" included India, Italy and Belgium. Gainers included the US, Australia and Switzerland.
The data comes from: Chiara Franzoni, Giuseppe Scellato, and Paula Stephan, May 2012. “Foreign Born Scientists: Mobility Patterns for Sixteen Countries,” National Bureau of Economic Research.