According to the article “I’m So Tired of Being Green”:

The Shelton Group's latest study, Energy Pulse 2007, revealed that between 2006 and 2007, Americans' enthusiasm for energy-efficient products and services fell across the board. Among its findings: the number of green or energy-efficient activities consumers said they participated in—such as recycling or riding a bike to work instead of driving—dropped from an average of 3.63 in 2006 to 3.0 last year.