World War II until its collapse, Soviet GDP (PPP) was the second-largest in the world, and third during the second half of the 1980s, although on a per-capita basis, it was behind that of First World countries. Compared to countries with similar per-capita GDP in 1928, the Soviet Union experienced significant growth. In 1990, the country had a Human Development Index of 0.920, placing it in the ‘high’ category of human development. It was the third-highest in the Eastern Bloc, behind Czechoslovakia and East Germany, and the 25th in the world of 130 countries. Energy The need for fuel declined in the Soviet Union from the 1970s to the 1980s, both per ruble of gross social product and per ruble of industrial product. At the start, this decline grew very rapidly but gradually slowed down between 1970 and 1975. From 1975 and 1980, it grew even slower, only 2.6%. David Wilson, a historian, believed that the gas industry would account for 40% of Soviet fuel production by the end of the century. His theory did not come to fruition because of the USSR's collapse. The USSR, in theory, would have continued to have an economic growth rate of 2–2.5% during the 1990s because of Soviet energy fields. However, the energy sector faced many difficulties, among them the country's high military expenditure and hostile relations with the First World. In 1991, the Soviet Union had a pipeline network of for crude oil and another for natural gas. Petroleum and petroleum-based products, natural gas, metals, wood, agricultural products, and a variety of manufactured goods, primarily machinery, arms and military equipment, were exported. In the 1970s and 1980s, the USSR heavily relied on fossil fuel exports to earn hard currency. At its peak in 1988, it was the largest producer and second-largest exporter of crude oil, surpassed only by Saudi Arabia. Science and technology The Soviet Union placed great emphasis on science and technology within its economy, however, the most remarkable Soviet successes in technology, such as producing the world's first space satellite, typically were the responsibility of the military. Lenin believed that the USSR would never overtake the developed world if it remained as technologically backward as it was upon its founding. Soviet authorities proved their commitment to Lenin's belief by developing massive networks, research and development organizations. In the early 1960s, the Soviets awarded 40% of chemistry PhDs to women, compared