The Sharpe ratio is calculated as the ratio between the return and the volatility.
Now, when I have a trading strategy that requires to be invested sometimes and to be flat other times, I assume 0% during the flat time. This results in 9.5% average annualized return and 9.6% annualized standard deviation. I could compute the Sharpe ratio simply by the ratio of the two. Now I have the option to add a coupon that yields 2% during the flat time. Is it then correct to add the 2% to the return, so the Sharpe ratio grows?