I don't think it has much to do with where the traffic is coming from. Instead, it relates to the quality of your Website's content, which in turn affects the quality of the ads displayed on your site.
How can the content quality make higher paying ads? I mean if I have a low quality adsense page with the same keywords as another site that has good quality content, how will google be able to put in the high paying ads on the good quality site?
For a proxy site from Iran you're doing just fine. To increase your earnings, you should increase your trafic. Do this by following the basic SEO techniques, and promote your site everywhere.
There are a few aspects of "quality" content that you have to look at. First, if you want higher paying clicks you need a higer paying niche. You could have the highest quality content about underwater basket weaving on the internet, however, there just aren't that many adwords advertisers bidding for that keyword phrase. Secondly, if you are focusing on a fairly high paying niche but your content sucks you will never get the visitors to you site to click on ads in the first place unless you are buying traffic.