The plant Oryza sativa is the major source of food for nearly one-half of the world's population. In China, Japan, Korea, the Philippines, India, and other countries of Asia, rice is far more important than wheat as a source of carbohydrates. In some countries of the Orient the consumption of rice per capita is estimated at 200–400 lb (90–180 kg) per year. In contrast, the yearly per capita consumption of rice in the United States is only about 8 lb (3.6 kg). The most important rice-producing countries are mainland China, India, and Indonesia, but in many smaller countries rice is the leading food crop. In the United States, rice production is largely concentrated in selected areas of Arkansas, California, Louisiana, and Texas.