Here is an eye-popping look at Facebook usage by Countries. This comprehensive analysis was done by a veteran blogger and public relations specialist, Nick Burcher.Note that the author used advertising information from Facebook for the statistical source.
An interesting challenge is to write down several country names, i.e., France, Italy, Russia, China, USA. Place a number next to each country with your estimation of usage. Then look at the chart and see how close you were to the reported number.
Read this post and the resulting comments about Facebook use in different countries.