Leonard0 - 3:50 pm on Apr 28, 2010 (gmt 0)
My CTR for April is about half of what it was in April 2009. It has been dropping steadily over that period compared to the corresponding months a year earlier. However, the CTR on my sites had been decreasing prior to that, though slower.
It was around April 2009 that interest-based ads started to roll out.
Luckily, increased impressions and EPC have maintained my revenues (so far, fingers crossed).