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Seasonally adjusted quarterly U.S. GDP from 1947(1) to 2018(3).
The format is: Time-Series [1:287] from 1947 to 2018: 2033 2028 2023 2055 2086 ...
http://www.stat.pitt.edu/stoffer/tsa4/ and http://www.stat.pitt.edu/stoffer/tsda/