I have run Adsense for about two weeks. The traffic are from different sources with different geos. At the beginning, it seems that CTR was quite good to be around more than 5%. But then it decreased gradually, now it going to be less than 2%. I have made no changes with my ads format or arragement in the site. Also, another observation, it seems that the rate of each click dropped gradually form 0.5$ on average to 0.25$ on average now. i wonder anyone has similar experience like me when you run your adsense.
Dont worry about these stats they vary a lot and dude its only two weeks that you have started adsense!! just wait and do some optimizations.. give the URL so that I can chk what's the problem may be thats the issue of ad placement.
your users are becoming blind to the ads, do something to change it up a little. Perhaps a color change? Location change?