8.9 billion cases of soda were sold in 2013, marking a 3 percent decline from 2012 and double previous years' declines. Sales dropped 1.2 percent in 2012 and 1 percent in 2011.
Despite the decline, Coca-Cola Co. and Dr. Pepper Snapple Group both gained market share. PepsiCo Inc., Coca-Cola's main business rival, lost market share.
Campaigns to combat the obesity epidemic in the U.S. have warned about the weight gain caused by consuming sodas. But even diet soda took a heavy hit with a 6.8 percent drop in sales for Diet Coke and a 6.9 percent drop for Diet Pepsi. The soda companies blame the continuous decline on concerns over artificial sweeteners.
The companies still believe they can see the industry bounce back. Dan Schafer, a spokesman for Coca-Cola, told ABC News the Atlanta company was "committed to returning our overall sparkling business to growth in the U.S."