Boys advocated laissez-faire, free-market, neoliberal, and fiscally conservative policies, in stark contrast to the extensive nationalization and centrally-planned economic programs supported by Allende. Chile was drastically transformed from an economy isolated from the rest of the world, with strong government intervention, into a liberalized, world-integrated economy, where market forces were left free to guide most of the economy's decisions. From an economic point of view, the era can be divided into two periods. The first, from 1975 to 1982, corresponds to the period when most of the reforms were implemented. The period ended with the international debt crisis and the collapse of the Chilean economy. At that point, unemployment was extremely high, above 20 percent, and a large proportion of the banking sector had become bankrupt. The following period was characterized by new reforms and economic recovery. Some economists argue that the recovery was due to an about-face turnaround of Pinochet's free market policy, since he nationalized many of the same industries that were nationalized under Allende and fired the Chicago Boys from their government posts. 1975–81 Chile's main industry, copper mining, remained in government hands, with the 1980 Constitution declaring them "inalienable," but new mineral deposits were open to private investment. Capitalist involvement was increased, the Chilean pension system and healthcare were privatized, and Superior Education was also placed in private hands. One of the junta's economic moves was fixing the exchange rate in the early 1980s, leading to a boom in imports and a collapse of domestic industrial production; this together with a world recession caused a serious economic crisis in 1982, where GDP plummeted by 14%, and unemployment reached 33%. At the same time, a series of massive protests were organized, trying to cause the fall of the regime, which were efficiently repressed. 1982–83 In 1982-1983 Chile witnessed a severe economic crises with a surge in unemployment and a meltdown of the financial sector. 16 out of 50 financial institutions faced bankruptcy. In 1982 the two biggest banks were nationalized to prevent an even worse credit crunch. In 1983 another five banks were nationalized and two banks had to be put under government supervision. The central bank took over foreign debts. Critics ridiculed the economic policy of the Chicago Boys as "Chicago way to socialism". 1984–90 After the economic crisis, Hernán Büchi became Minister of Finance from 1985 to 1989, introducing a return to a free market