Although significant oil discoveries in 1976 allowed a temporary recovery, the windfall from petroleum sales also allowed continuation of Echeverría's destructive fiscal policies. In the mid-1970s, Mexico went from being a net importer of oil and petroleum products to a significant exporter. Oil and petrochemicals became the economy's most dynamic growth sector. Rising oil income allowed the government to continue its expansionary fiscal policy, partially financed by higher foreign borrowing. Between 1978 and 1981, the economy grew more than 8 percent annually, as the government spent heavily on energy, transportation, and basic industries. Manufacturing output expanded modestly during these years, growing by 8.2 percent in 1978, 9.3 percent in 1979, and 8.2 percent in 1980.