Earnings are variable, based on CTR :

With the Smart pricing idea, your income increases, according to each of your channel's CTR rate.

Now this is very important : It's account-wide, not channel wide. So if you have a good CTR (5%-50%) for one website, and you include it in the same account with a 0.04# CTR website, you will loose money.

Remove all the websites (from your account) that don't have atleast a 5% CTR (or depending on your overall CTR, remove the ones that are really lower than your average), or you'll affect the income of all other good converting website.

Increase in CTR depends on increase in web traffic or CTR

CTR increase depends upon the keywords you are targeting, look of you website, quality of its content, placement of adsense ads, page optimization, and various other factors.

NOTE: For websites with poor quality, placing ads before start of content works well.

If you develop low quality content website, it will likely to give CTR with low priced ads , but if you develop quality content then you may get low CTR but with high quality ads and regular visitors. Proper positioning of ads on your website/Blog has direct impact on your CTR. Change the location of the ads and watch the changes in your CTR regurarly.

So all we need to keep "Quality Content"...