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 use 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? (LO1)