The countries has high cpc rate because of high advertising investment budget per click of their brand promotion.
- South Africa,
- Middle East
- United Arab emirates
If you are getting more traffic from countries like i mention, then you will be paid more per cpm, rpm and cpm for every clicks of your Ads publish in your blog or commercial websites,
more on : Top Secret To Increase Adsense Daily Revenue Income Guaranteed 3 Days .
If you don't satisfied what we mention above, their always a second options to increase Adsense cpc rate,
Cost Per Click (CPC) or Pay Per Click (PPC)- Webmaster Earns some bucks by simply clicks per Ads on their Advertisements by their site visitors. CPC is varies by county to country. For example in India, CPC ratio is in between 0.06 $ to 0.4 $Traffic sources is the another very important topic to optimize for getting higher CPC ads, like in India or Asian traffic, not more than 0.4$ CPC you get but for western country traffic you can get up to 2$ to 4$ CPC ads.
So you need to try to write such content to attract more visitors from western counties also
more on: Best Practice To Increase Adsense CPC Rate.