Do not listen to the majority of posts here. It depends entirely on Ad Placement and site content. Video sites for instance do not attract a high CTR.
Currently this month, all my sites equate to 244,166 impressions but with this, you have to include pages with multiple Ad units on them, that counts at 2 impressions per page load - bear that in mind.
With 244,166 page impressions, my monthly earnings only equate to $170.53. It depends entirely on your keywords, Ad placement (CTR), Ad Units (Link Units/Ad Units/Image Units) and I'm sure a lot of other things I've failed to mention.
Just grow your site naturally and don't aim for figures expecting massive returns. Good Content, Ad Placement, the right Ad Units and traffic is all you should be working towards.