The St. Louis Fed's FRED database has historical info on the federal funds rate
Wiki says that "In the United States, the federal funds rate is the interest rate at which depository institutions (banks and credit unions) lend reserve balances to other depository institutions overnight, on an uncollateralized basis."
Here's the graphic - click the picture for a full size version:
(source St. Louis Fed ) |
Seemed to me the trend was gradually going up and then peaking around 1980 then going down. I used Excel to plot a (polynomial) trend line :
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