From 1991 to​ 2000, the U.S. economy had an annual inflation rate of around 2.76​%. The historical annual nominal​ risk-free rate for this same period was around 5.71​%. Using the approximate nominal interest rate equation and the true nominal interest rate​ equation, compute the real interest rate for that decade. What is the estimated real interest rate using the approximate nominal interest rate equation for that​ decade?