The USA has the highest research and development expenditures in the world. In 2008 it was almost $400 billions or 2.8% of GDP. The gap between the U.S. and other countries is essential. The rest from the top five (Japan, China, Germany and France) only taken together spend as much as the U.S.
The model of R&D expenditures differs from country to country. For example, expenditures on basic research account for 17% in total R&D expenditures in the U.S. compared to only 5% in China.