You buy ten (10) S&P500 index December futures contracts. Currently, S&P500 futures price is $3,000. The contract size is 50 and initial margin requirement is 6%. A month later, futures price increases 2.1%. Find the rate of return. (Report in percentage up to 2 decimal points. If your answer is 12.345%, then enter 12.35 instead of 0.1234.) (margin for error: +/- 1%)