A few days ago, a paper was posted at the arXiv, in which the authors looked at where the top 10% cited scientific papers come from. The distribution is not terribly surprising: Most papers come from Europe, North America and Japan, followed by Singapore, Hong Kong and Australia. But, looking at the maps, you notice a few interesting things. If you compare the maps for Physics, Chemistry and Psychology, you see that the US is dominant in Psychology, but less so in the exact sciences. This is even more apparent for Canada: Most of the green dots on the Psychology map are not even present on the Chemistry map. In Europe the difference between Psychology and the exact sciences doesn't appear to be as pronounced, and in Singapore and Hong Kong it's the other way around.
Image: Citation map for Psychology [source]
Bornmann, L., & Leydesdorff, L. (2011). Which cities produce worldwide more excellent papers than can be expected? A new mapping approach--using Google Maps--based on statistical significance testing. 1103.3216. Retrieved from http://arxiv.org/abs/1103.3216