Has anyone experience a drop in their ctr with their Adsense ads in say the last six months. I have used Adsense for over 5 years on a network of sites and have always had pretty constant and reliable results. However in the last six months my CTR has dropped by more than half. I haven't changed a thing on my site, my traffic has not changed and I cant think of anything else that would have impacted my CTR like that. I was making decent money with Adsense but after a drop like this it pretty much changes everything.
Does anyone have any ideas on what could have caused this? Has it happened to anyone else.