The following data show U.S. retail sales of canoes from 1991 through 2008, with data in thousands of boats.

a. Construct a graph of the time series. Does the overall trend appear to be upward or downward?
b. Construct a three-year centered moving average for this series.
c. Using the constant α = 0.3, fit an exponentially smoothed curve to the original time series.
d. Repeat part (c) using α = 0.7. How has the new value for the constant affected the smoothness of the fitted curve?

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Sales thousands) 72.3 78.0 89.7 99.8 97.8 92.9 103.6 107.8 121.0 Sales (thousands) Year 1992 1993 1994 1995 1996 1997 1998 1999 Year 2000 2001 2002 2003 2004 2005 2006 2007 2008 105.8 100.0 86.7 93.9 77.2 99.9 99.6 73.7 2