Peter Cardillo, chief market economist at Rockwell Global Capital, weighs in on the stronger-than-expected revision to third-quarter gross domestic product and if the U.S. economy can sustain its current growth in 2014. The Commerce Department said in its third and final estimate on Friday the U.S. economy grew at a 4.1 percent annual rate during the third-quarter instead of the 3.6 percent pace reported earlier this month.