sentences:  To generate essential foreign exchange, the Ortega administration continued to support an upscale, high-tech agroexport sector, but returns on its investment diminished.By 1990 only one-quarter of the pre-1979 area planted in cotton, one of the leading foreign exchange earners in the 1970s, was still under cultivation.Despite an established priority for food production, food imports to Nicaragua grew enormously from the mid-1970s to the mid-1980s.