Statements of Cash Flows - USD ($)	12 Months Ended
Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Cash Flows from Operating Activities:
Net income (loss)	$ 26,763,267	$ (15,190,394)	$ 15,451,090
Adjustments to reconcile net income (loss) to net cash provided by (used in) operating activities:
Unrealized (gain) loss on open futures contracts	(7,451,120)	11,877,420	(3,255,030)
(Increase) decrease in receivable from General Partner	1,610	249,791	(141,688)
(Increase) decrease in dividends receivable	(8,304)	(821)	(6,613)
(Increase) decrease in interest receivable	(3,515)	8,188	(9,575)
(Increase) decrease in prepaid insurance	(588)	(527)	(311)
(Increase) decrease in ETF transaction fees receivable	0	350	350
Increase (decrease) in General Partner management fees payable	2,391	(11,475)	(12,926)
Increase (decrease) in professional fees payable	(72,583)	(52,980)	135,701
Increase (decrease) in brokerage commissions payable	0	(2,500)	(1,860)
Increase (decrease) in directors' fees payable	349	778	255
Net cash provided by (used in) operating activities	19,231,507	(3,122,170)	12,159,393
Cash Flows from Financing Activities:
Addition of partnership shares	17,034,820	41,996,934	40,082,469
Redemption of partnership shares	(32,720,529)	(51,328,625)	(71,195,236)
Net cash provided by (used in) financing activities	(15,685,709)	(9,331,691)	(31,112,767)
Cash and Cash Equivalents, Period Increase (Decrease).	3,545,798	(12,453,861)	(18,953,374)
Total Cash, Cash Equivalents and Equity in Trading Accounts, beginning of period	80,057,642	92,511,503	111,464,877
Total Cash, Cash Equivalents and Equity in Trading Accounts, end of period	$ 83,603,440	$ 80,057,642	$ 92,511,503

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