Health advocates see an encouraging trend in the fight against obesity and diet-related disease: Americans are drinking less soda pop. Per capita consumption of carbonated soft drinks has declined for 11 straight years, according to data from Beverage Marketing Corporation. Per capita consumption of sugary soft drinks is 22 percent below its peak in 1998, according to the trade publication Beverage Digest and calculations by the Center for Science in the Public Interest.

To be sure, even with the declines in consumption in recent years, Coca-Cola, PepsiCo, Dr. Pepper Snapple, and other companies produced 9.4 billion cases of sugary soda and energy drinks in 2009. At the 1998 peak, when CSPI first published its Liquid Candy report, companies were producing 638 8-ounce servings of non-diet soft drinks per person. By 2009, that figure was down to 543 8-ounce servings. Still, that’s about 140 empty calories a day, for every man, woman, and child in the United States.

“The recognition that soda pop promotes weight gain and disease is gaining traction, contributing to the steady decline in soda consumption,” said CSPI executive director Michael F. Jacobson. “Ten years from now, it would be great to see that Americans are drinking a can and a half a week, instead of a can and a half a day.”

Besides concern over obesity, Jacobson said that the growing popularity of bottled water, the low-carb Atkins and South Beach diets, bans on soft drinks in schools, and rising unemployment rates are all partly responsible for the decline in soda consumption.

According the United States Department of Agriculture and Beverage Digest, the proportion of carbonated soft drinks that are non-caloric diet drinks increased from 23 percent to 30 percent between 1998 and 2009.