Diet sodas contain no or little sugar and provide no calories. Instead, they are artificially sweetened with aspartame, acesulfame K, sucralose, Stevia, or other nonnutritive chemicals. See artificial sweeteners and stevia. Even though there is little evidence to support the idea that diet drinks help with weight loss or maintenance, they account for 30 percent of soda sales in America. Their most frequent drinkers are older, white, married, and well-educated females. Sales of diet drinks are also declining in America as a result of concerns about their slightly bitter aftertaste and unnatural sweeteners. On a worldwide basis, diet drinks comprise 12 percent of soda sales, but the percentages vary widely, from 3 percent or below in Asian countries to as much as 35 percent in Australia.