On December 15, 2015, the FOMC raised the target range for the market federal funds rate by 25 basis points (bp) to a range of ¼ to ½ percent. It also instructed the Open Market Desk at the Federal Reserve Bank of New York to engage in overnight reverse repurchase agreements (ON RRPs) with eligible participants at an offering rate of ¼ percent. To see the impact, plot (on a “Weekly, ending Wednesday” basis beginning July 15, 2015) the interest rate on excess reserves (FRED code: IOER) and the effective federal funds rate (FRED code: FF). Explain the plot, noting the impact of the FOMC decision on these two interest rates as well as the implicit role played by the offering rate on ON RRPs.