A large portion of the country's manufactured exports is dependent on raw materials such as cotton and hides that are part of the agriculture sector, while supply shortages and market disruptions in farm products do push up inflationary pressures. The country is also the fifth-largest producer of cotton, with cotton production of 14 million bales from a modest beginning of 1.7 million bales in the early 1950s; is self-sufficient in sugarcane; and is the fourth-largest producer in the world of milk. Land and water resources have not risen proportionately, but the increases have taken place mainly due to gains in labour and agriculture productivity. The major breakthrough in crop production took place in the late 1960s and 1970s due to the Green Revolution that made a significant contribution to land and yield increases of wheat and rice. Private tube wells led to a 50 percent increase in the cropping intensity which was augmented by tractor cultivation. While the tube wells raised crop yields by 50 percent, the High Yielding Varieties (HYVs) of wheat and rice led to a 50–60 percent higher yield. Meat industry accounts for 1.4 percent of overall GDP.