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v3.19.1

FINANCIAL HIGHLIGHTS (Per Unit Performance Data and Other Supplemental Financial Data) (Details) - $ / shares | 3 Months Ended
--- | ---
Mar. 31, 2019 | Mar. 31, 2018
Per Share Operating Performance: |  |  |
Net asset value, beginning of period |  | $ 17.82 | $ 21.05
Total income (loss) |  | 4.75 | 1.64
Total expenses |  | (0.05) | (0.04)
Net increase (decrease) in net asset value |  | 4.70 | 1.60
Net asset value, end of period |  | $ 22.52 | $ 22.65
Total Return |  | 26.37% | 7.60%
Ratios to Average Net Assets |  |  |
Total income (loss) |  | 22.55% | 7.71%
Management fees | [1] | 0.60% | 0.60%
Expenses excluding management fees | [1] | 0.31% | 0.21%
Net income (loss) |  | 22.32% | 7.51%
[1] | Annualized.

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