I have best results from loans and forex stuff and it depends from country.. US I guess gives more that EU countries
Nowadays its the thing from ancient times. These days cpc is getting low and low.. Well i always wish to have higher cpc like you have ... that's really impressive earning
your site keyword may earn you not the ad unit that we placing ... normally image ads earns more cpc as well ctr than text link ads...
$20 per click is really good. Hope you get more click like these or just more clicks in general. I am just working with adsense as a means to prove earnings on some of my sites so I can flip them.