Plot since 1999, without recession bars, the real exchange rate between U.S. goods and euro-area goods according

Question:

Plot since 1999, without recession bars, the real exchange rate between U.S. goods and euro-area goods according to equation (2) in the text. Use the consumer price index (divided by 2.37 to set a common base year of 2015=100 for the U.S. and euro-area indexes) for the price of U.S. goods (FRED code: CPIAUCSL).Use the harmonized index of consumer prices for the euro area goods (FRED code:CP0000EZ19M086NEST), and the U.S. dollar-euro exchange rate (FRED code: EXUSEU). Why might this measure of the real exchange rate be persistently below unity since 2003?

Exchange Rate
The value of one currency for the purpose of conversion to another. Exchange Rate means on any day, for purposes of determining the Dollar Equivalent of any currency other than Dollars, the rate at which such currency may be exchanged into Dollars...