context: Some economists have stated that Reagans policies were an important part of bringing about the third longest peacetime economic expansion in U.S. history.  During the Reagan administration, real GDP growth averaged 3.5%, compared to 2.9% during the preceding eight years.  The annual average unemployment rate declined by 1.7 percentage points, from 7.2% in 1980 to 5.5% in 1988, after it had increased by 1.6 percentage points over the preceding eight years.  Nonfarm employment increased by 16.1 million during Reagans presidency, compared to 15.4 million during the preceding eight years, while manufacturing employment declined by 582,000 after rising 363,000 during the preceding eight years. Reagans administration is the only one not to have raised the minimum wage.  The inflation rate, 13.5% in 1980, fell to 4.1% in 1988, due to the Federal Reserve increasing interest rates (prime rate peaking at 20.5% in August 1981).  The latter contributed to a recession from July 1981 to November 1982 during which unemployment rose to 9.7% and GDP fell by 1.9%. Additionally, income growth slowed for middle- and lower-class (2.4% to 1.8%) and rose for the upper-class (2.2% to 4.83%).
question: How many percentage did the income growth decline for the middle and lower class?
answer: .6