CPM and Price of a Super Bowl Ad Over Time

Yesterday the New York Times reported that the average price for a Super Bowl ad was between $3.7 million and $3.8 million this year. Here is the average price of a Super Bowl spot over time, adjusted for inflation:

CPM represents the cost for every thousand viewers. The ratings for each game are from Zap2It. I found historical price data on Wikipedia, although I do not completely trust the numbers; I edited what appears to be an overly precipitous price drop after the dot com bubble burst. That said, others have been through this exercise before and the graphs look quite similar, so I believe the data are approximately correct.