Hello, i have a few popullar apps on the play store, they didnt have ads but now i decided to start making something about this, so i implemented admob insterstitial ads.
In the first week i had 500 000 impressions and 4000 clicks, this just gave me 200$
Is this normal?
Seems about right, the first few months of the year are very bad 
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0.05$ CPC is not low, it is quite normal, however, your CTR (0.8%) is very low, maybe you can try to increase it by showing at the right time and place
it is low for interstitial.
It is normally 0.7 ecpm for asia countries. I believe you are in these countries.