Hello
I’ve recently uploaded a game in Google Play Store. And i got 92 impression (60 completed) in the United Kingdom and i got an eCPM of $2.28. And i got 252 impression (118 completed) in Bulgaria and got an eCPM of $0.00. What’s the problem?? Ive got the biggest “fan base” in Bulgaria and sadly this is happening please help if you can!
Thank you! 
This is normal. The advertisers pay extra if their ads are presented to people from richer countries (especially if those people click to install the apps which are advertised).
Also, your sample data is too small and too granular to be able to extract a definitive trend. I expect the eCPM for UK to stabilize in time at about $3 - $4, and the one for Bulgaria will be at about $1.