You buy a 2x S&P 500 ETF and hold it for three days. The S&P 500 Index returns for these three days are 6.68%, -14.91%, and 10.50%. What's the tracking error of the three-day holding period return you experienced? That is, assuming the three-day holding period return of the S&P 500 Index is x%, ideally, you should have a return of 2x%. But your three-day holding period return of the 2x S&P 500 ETF is y%. What is (y-2x)%? Enter a number with two decimal points. Answer the question in percentage terms, i.e., if the answer is 20%, enter 20.00