A reported $3.5 million / 30 second ad for this season's represents a 13% increase over last year's $3.1 million.
That 13% increase compares to changes of +5%, -1%, +11%, and 13% over the previous four years. The trend is generally upwards, but the 2010 dip shows that the economy does matter. Less numerically inclined folks might have drunk the social media kool aid and opined that social media drove the increase this year without any actual evidence.
Here are the figures for the previous five seasons via nielsenwire:
Interesting how Q1 primetime TV advertising costs have no clear trend over the past 5 seasons.