where fires of hardwoods are kept on continuous or intermittent low smoulder, and takes between three days and ten weeks, depending on the process and the tobacco. Fire curing produces a tobacco low in sugar and high in nicotine. Pipe tobacco, chewing tobacco, and snuff are fire-cured. Flue-cured tobacco was originally strung onto tobacco sticks, which were hung from tier poles in curing barns (Aus: kilns, also traditionally called 'oasts'). These barns have flues run from externally fed fire boxes, heat-curing the tobacco without exposing it to smoke, slowly raising the temperature over the course of the curing. The process generally takes about a week. This method produces cigarette tobacco that is high in sugar and has medium to high levels of nicotine. Most cigarettes incorporate flue-cured tobacco, which produces a milder, more inhalable smoke. It is estimated that 1 tree is cut to flue-cure every 300 cigarettes, resulting in serious environmental consequences. Sun-cured tobacco dries uncovered in the sun. This method is used in Turkey, Greece, and other Mediterranean countries to produce oriental tobacco. Sun-cured tobacco is low in sugar and nicotine and is used in cigarettes. Some tobaccos go through a second stage of curing, known as fermenting or sweating. Cavendish undergoes fermentation pressed in a casing solution containing sugar and/or flavoring. Global production Trends Production of tobacco leaf increased by 40% between 1971, when 4.2 million tons of leaf were produced, and 1997, when 5.9 million tons of leaf were produced. According to the Food and Agriculture organization of the UN, tobacco leaf production was expected to hit 7.1 million tons by 2010. This number is a bit lower than the record-high production of 1992, when 7.5 million tons of leaf were produced. The production growth was almost entirely due to increased productivity by developing nations, where production increased by 128%. During that same time, production in developed countries actually decreased. China's increase in tobacco production was the single biggest factor in the increase in world production. China's share of the world market increased from 17% in 1971 to 47% in 1997. This growth can be partially explained by the existence of a low import tariff on foreign tobacco entering China. While this tariff has been reduced from 66% in 1999 to 10% in 2004, it still has led to local, Chinese cigarettes being preferred over foreign cigarettes because of their lower cost. Major producers Every year,