Estimates of food waste in the United States range from 35 million tons to 103 million tons. In a study done by National Geographic in 2014, Elizabeth Royte indicated more than 30 percent of food in the United States, valued at $162 billion annually, isn't eaten. The University of Arizona conducted a study in 2004, which indicated that 14 to 15% of United States edible food is untouched or unopened, amounting to $43 billion worth of discarded, but edible, food. In 2010, the United States Department of Agriculture has come forth with estimations from the Economic Research Service that approximates food waste in the United States to be equivalent to 141 trillion calories.