From 2006 to today the cost important exact match keywords for my campaigns (maintaining the same position) have increased about 50%. Has anyone calculated what the overall inflation of adwords has been over time?
I've done this sort of compilation before with the data from my clients. In general, I don't find an increase, not 50%, and if I do, it can be easily explained.
It's often hard to tell however as there's so many variables. Clients don't tend to have good QS, that's why they hire me. For some, I've advised to increase bids to get higher positions. Competition will have an effect: numbers and their bid patterns. But looking at a few long term campaigns that I've done myself, some CPCs have gone up, others about the same and some gone down.