number of factors. First, organic farmers do not rely on synthetic fertilizer and pesticide inputs, which can be costly. In addition, organic foods currently enjoy a price premium over conventionally produced foods, meaning that organic farmers can often get more for their yield. The price premium for organic food is an important factor in the economic viability of organic farming. In 2013 there was a 100% price premium on organic vegetables and a 57% price premium for organic fruits. These percentages are based on wholesale fruit and vegetable prices, available through the United States Department of Agriculture's Economic Research Service. Price premiums exist not only for organic versus nonorganic crops, but may also vary depending on the venue where the product is sold: farmers' markets, grocery stores, or wholesale to restaurants. For many producers, direct sales at farmers' markets are most profitable because the farmer receives the entire markup, however this is also the most time and labour-intensive approach. There have been signs of organic price premiums narrowing in recent years, which lowers the economic incentive for farmers to convert to or maintain organic production methods. Data from 22 years of experiments at the Rodale Institute found that, based on the current yields and production costs associated with organic farming in the United States, a price premium of only 10% is required to achieve parity with conventional farming. A separate study found that on a global scale, price premiums of only 5-7% were needed to break even with conventional methods. Without the price premium, profitability for farmers is mixed. For markets and supermarkets organic food is profitable as well, and is generally sold at significantly higher prices than non-organic food. Energy efficiency Compared to conventional agriculture, the energy efficiency of organic farming depends upon crop type and farm size. Two studies – both comparing organically- versus conventionally-farmed apples – declare contradicting results, one saying organic farming is more energy efficient, the other saying conventionally is more efficient. It has generally been found that the labor input per unit of yield was higher for organic systems compared with conventional production. Sales and marketing Most sales are concentrated in developed nations. In 2008, 69% of Americans claimed to occasionally buy organic products, down from 73% in 2005. One theory for this change was that consumers were substituting "local" produce for "organic" produce.The Hartman Group Organic Marketplace Reports . Distributors The USDA requires