The author needs to check his data. The Federal Funds rate is the rate the Fed charges member banks for short term loans. In most cases, “going to the window” for these funds is to cover intra-day shortages on reserve requirements. The rate peaked under Carter (over 20%!) and, except for a short dip in the early 1990’s, didn’t get under 4% until 2000. See: https://www.macrotrends.net/2015/fed-funds-rate-historical-chart
You meant the Discount rate.