One Google AdWords advertiser shares;
In my case ICR's have tended to fluctuate between 5.5% and 9.0%, for campaigns where content bids are ~1/5th search bids and still accounting for ~40% of total clicks.
An other advertiser shares;
Depending on the global region, I'm anywhere from 2.5% to 7.5%... the US is near the low end of the range, Asian countries at the high end.
What is your ICR? And more importantly, do you think it is accurate? Forum discussion at WebmasterWorld.