After the reconstruction of the economy in the wake of the destruction caused by the Russian Civil War was completed and after the initial plans of further industrialization were fulfilled, the explosive growth slowed down until the period of Brezhnev stagnation in the 1970s and 1980s. Led by the creation of NAMI and by the GAZ copy of the Ford Model A in 1929, industrialization came with the extension of medical services, which improved labor productivity. Campaigns were carried out against typhus, cholera and malaria; the number of physicians increased as rapidly as facilities and training would permit; and death and infant mortality rates steadily decreased. As weighed growth rates, economic planning performed very well during the early and mid-1930s, World War II-era mobilization, and for the first two decades of the postwar era. The Soviet Union became the world's leading producer of oil, coal, iron ore and cement; manganese, gold, natural gas and other minerals were also of major importance. However, information about the Soviet famine of 1932–1933 was suppressed by the Soviet authorities until perestroika. To some estimations, in 1933 workers' real earnings sank on more than 11.4% from 1926 level, though it needs an adjustment due to elimination of unemployment and perks at work (as, inexpensive meals). Common and political prisoners in labor camps were forced to do unpaid labor and communists and Komsomol members were frequently "mobilized" for various construction projects. The German invasion of World War II inflicted punishing blows to the economy of the Soviet Union, with Soviet GDP falling 34% between 1940 and 1942. Industrial output did not recover to its 1940 level for almost a decade. In 1961, a new redenominated Soviet ruble was issued. It maintained exchange parity with the Pound Sterling until the dissolution of the Soviet Union in 1991. After a new leadership, headed by Leonid Brezhnev, had come to power, attempts were made to revitalize the economy through economic reform. Starting in 1965, enterprises and organizations were made to rely on economic methods of profitable production, rather than follow orders from the state administration. By 1970, the Soviet economy had reached its zenith and was estimated at about 60 percent of the size of the United States in terms of the estimated commodities (like steel and coal). In 1989, the official GDP of the Soviet Union was $2,500 billion while the GDP of the United States was $4,862 billion with per capita income figures as $8,700 and $19,800 respectively.