Between 1945 and 1975, forest cover in Thailand declined from 61% to 34% of the country's land area. Over the succeeding 11 years, Thailand lost close to 28% of all of its remaining forests. This means that the country lost 3.1% of its forest cover each year over that period. An estimate by the World Wildlife Fund concluded that between 1973 and 2009, 43% of forest loss in the Greater Mekong subregion occurred in Thailand and Vietnam. The Thai Highlands in northern Thailand, the most heavily forested region of the country, were not subject to central government control and settlement until the second half of the 19th century when British timber firms, notably the Bombay Burmah Trading Corporation and the Borneo Company Limited, entered the teak trade in the late-1880s and early-1890s. The Royal Forest Department, created in 1896 and headed by a British forester until 1925, sought to conserve the forests against the worst business practices of British, Thai, and Chinese timber firms who worked in the region.