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Assume that a firm has weighted average cost of capital of 3.6% with a corporate tax rate of 21%. The pre-tax cost of debt is 3.1%. In case the firm would have no debt, the cost of equity for the firm would be 5.2%. However, the firm currently has a debt-to-equity ratio of 0.7. By how much would the WACC change if the firm would change their debt-to-equity ratio to 0.8? Please enter your result in percentage (e.g. increase in 3.5% would be 3.5) and round to one digit