Worldwide, more water—approximately 70 percent of total withdrawals—is used for agricul­tural purposes than for any other reason. Irrigation of arid and semiarid lands has become increasingly important worldwide in efforts to pro­duce enough food for burgeoning populations, and since 1955 the amount of land being irrigated worldwide has tripled. The World Resources Institute estimates that three-fourths of the agricultural land that is currently irrigated, some 200 million hectares (494 million acres), is in developing countries. Asia has more agricultural land under irrigation than do other regions, with China, India, and Pakistan accounting for most of it. It is projected that water use for irrigation will continue to increase in the 21st century, but at a rate than in the last half of this century.