Working with Adsense we webmasters look for ways to improve our CTR, but what's more important CPC. We can improve our CPC in many ways, like switching to recommended ad formats, providing highly targeted content. But in my opinion and experience, CPC varies for countries. I have found that most CPC came from USA, and less CPC from so-called developing countries, like India, Egypt and other.
I know people will object me, but I'm NOT sharing CPC rates I'm facing, working with mine sites (including this blog) - you may, and may not take serious these data - I'll one more time inform you, that CPC may vary for you, there are many factors affecting it - which you may never find out 100% sure. But tendencies I have found for my sites are as follow:
I have removed data - because it may violate Google TOS
As said, your data may vary - depending on niche you are working on, quality of content and other. These data ar more for me - to compare in future.