I've been with AdSense since July 2003, crazy early days when we'd get 6% CTR on some days. AdSense stayed quite stable until about 2007, at which point the bleed started and google squeezed us harder and harder despite massive increases in traffic.
we have a metric that we have always kept a watch on: earnings per million ad impressions. On a chart, it's a sad site, a study in subsidence.
In 2004, it was about $3000. In 2014, it was $1200, last year it was $600. Our traffic has increased massively, but we don't get more bang for our buck. Far from it. We are, as Bono once sang, running to stand still. There are more sites on the internet, people are more ad blind, blockers are everywhere. It's not all Google's fault, obviously.
i was interested if others kept track of this type of long term trends. Generally, our CTR has quartered and our CPC has halved over the period of 20+ years.
