I signed up to this forum just to provide my $0.02 on this post. To wit, if you're complaining about irregular eCPMS among different tiers, countries etc; you need to be using an ad mediation service such as HeyZap. It's free for publishers and combines the likes of Admob, UnityAds, Facebook Audience and more into a single, simple SDK. The benefit of this is that HeyZap will take care of everything for you. It'll rank the ad networks against each other depending on the user's demographics, therefore the highest bid between each platform will be served to individual users.