energy information administration annual review 2005 xix perspectives 18 97 in 1970 1950 1960 1980 1990 2000 0 20 40 60 80 100 120 quadrillion btu the united states was self sufficient until late 1950s when consumption began to outpace domestic production at that point nation import more fill gap net imported accounted for 30 percent of all consumed figure 1 overview exports imports 5 10 15 25 thousand per chained doll a 3 use dollar gross product after amount produce s worth output goods and services trended down decline resulted from efficiency improvements structural changes econ omy level 50 below 17 99 8 real dollars 200 300 400 500 million
