Americans may be experiencing sticker shock when it comes to their grocery bills: the U.S. Labor Department reported that wholesale food prices jumped 3.9 percent in January to February, the highest monthly increase in 36 years. Economists believe that prices will remain high due to a falling U.S. dollar, weaker than expected crop yields, civil and political unrest in the Middle East, high oil prices and violent weather patterns. "Food prices have been rising a lot faster, because underlying costs have really shot up. You're seeing some ingredients up 40%, 50%, 60% over last year," U.S. Department of Agriculture economist Ephraim Leibtag told the Los Angeles Times. "When you see wheat prices close to 80% up, that's going to ripple out to the public." According to the report, Americans typically spend about 10 percent of their income on food, but the USDA has projected that food prices will rise 3 to 4 percent this year.