That's an absolute decrease of 209 megatonnes CO2, from 2011 to 2012.
Energy-related carbon dioxide emissions have declined in five of the last seven years and are the lowest they have been since 1994.
GDP was up 2.8% last year, and energy intensity -- energy use per unit of GDP -- dropped 5.1% in a single year.
The carbon intensity of the US is now 0.34 tonnes CO2 per 2009-dollar, down from 0.88 t CO2/$2009 in 1973, the earliest year I have statistics for.
The EIA writes,
With population growth of about 0.7 percent, per capita output rose by about 2 percent in 2012. The emissions decline was the largest in a year with positive growth in per capita output and the only year to show a decline where per capita output increased 2 percent or more. However, emissions would have increased by about 143 MMTCO2 if the energy and carbon intensities had not decreased at the rates they did.and gives this chart for 2012:
Unfortunately, no matter what the annual decline, it never seems enough (because it isn't).