From 1919 through 1921, a combination of poor rice harvests and speculative buying caused unprecedented rice shortages in Southeast Asia and led to imposition of government controls over the rice industry. Because there were large workforces in South and Southeast Asia entirely dependent upon imported rice, the shortages were potentially very serious. Malaya and the East Coast Residency of Sumatra, for example, exported non-edible primary products such as tobacco, rubber and tin, and imported rice from Burma and Siam. Two-thirds of the rice consumed each year in Malaya, and one-half of that used in Sumatra's East Coast Residency, was imported, and local food production fell far short of the minimum needed if imported grain could not be obtained. Tea cultivation in Ceylon, tobacco and rubber planting in British North Borneo, and sugar planting in the Philippines were conducted along much the same lines.