Count total users on Facebook, grouped by country

How do I count total开发者_Python百科 users in Facebook grouped by country, similar to http://www.checkfacebook.com/

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1. Go to http://www.facebook.com/advertising/.
2. Click the button to create an ad.
3. Experiment with the 'Country' setting. Note that the "Estimated Reach" box will tell you how many people are in the currently selected countr(y/ies).

If you're clever, you could even script something to scrape this information automatically for you.