Since the 1980s, the US real interest rates (denoted by "r") have been gradually decreasing. The research shows that the decline in the equilibrium (long-run) real interest rate (denoted by "r*") has contributed to the decline in "r". Use the saving and investment analysis from class to explain (in words or graphically) the decline in r* - be sure to provide a couple of specific factors that contributed to the decline (and how these factors affected saving and/or investment). Hint: To ease exposition, you can assume that the economy is closed.