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Statements of Cash Flows - USD ($) | 12 Months Ended
--- | ---
Dec. 31, 2017 | Dec. 31, 2016 | Dec. 31, 2015
Cash Flows from Operating Activities: |  |  |
Net income (loss) | $ (193,443,975) | $ 98,732,182 | $ (245,141,023)
Adjustments to reconcile net income (loss) to net cash provided by (used in) operating activities: |  |  |
(Increase) decrease in commodity futures trading account - cash and cash equivalents | (56,035,182) | (20,024,673) | 201,219,414
Unrealized (gain) loss on open futures contracts | (18,286,173) | 63,973,835 | (269,221,125)
(Increase) decrease in dividends receivable | (2,090) | (14,212) | 6,665
(Increase) decrease in interest receivable | (11,573) | 0 | 0
(Increase) decrease in directors' fees and insurance receivable | 0 | 26,732 | (9,371)
(Increase) decrease in prepaid registration fees | 29,526 | 404,792 | 58,107
(Increase) decrease in ETF transaction fees receivable | 0 | 0 | (2,000)
Increase (decrease) in payable due to Broker | (44,770,339) | 3,906,389 | 40,863,950
Increase (decrease) in General Partner management fees payable | 9,112 | 53,400 | (114,291)
Increase (decrease) in professional fees payable | 455,541 | (713,180) | (162,250)
Increase (decrease) in brokerage commissions payable | (12,400) | 1,450 | 11,000
Increase (decrease) in directors' fees and insurance payable | 2,928 | 5,417 | 0
Increase (decrease) in license fees payable | (7,138) | (1,954) | (6,027)
Net cash provided by (used in) operating activities | (312,071,763) | 146,350,178 | (272,496,951)
Cash Flows from Financing Activities: |  |  |
Addition of partnership shares | 1,786,316,120 | 726,382,450 | 1,626,007,655
Redemption of partnership shares | (1,446,127,327) | (803,743,255) | (1,489,547,553)
Net cash provided by (used in) financing activities | 340,188,793 | (77,360,805) | 136,460,102
Net Increase (Decrease) in Cash and Cash Equivalents | 28,117,030 | 68,989,373 | (136,036,849)
Cash and Cash Equivalents, beginning of year | 522,819,857 | 453,830,484 | 589,867,333
Cash and Cash Equivalents, end of year | $ 550,936,887 | $ 522,819,857 | $ 453,830,484

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