Why does Adsense keep decreasing?

[ttvyaboydes]

I have been checking AdSense's daily and hourly click numbers for a few days. I noticed that the earnings fluctuate, with 17 clicks earning 3 lira, then dropping to 2 lira within 5 minutes, increasing again with 15 clicks, only to drop once more. With around 1500 visitors and 8000 ad impressions, the result was 15 clicks and earnings down to 2.50 lira. I'm not sure of the reason behind this. Any explanations?