The amounts spent in vending machines in the United States, in billions of dollars, for the years 1999 through 2003 are given below. Determine the least squares trend equation.
Year Code X Vending Machine Sales ($ billions) Y
1999 1 17.5
2000 2 19.0
2001 3 21.0
2002 4 22.7
2003 5 24.0
By using regression analysis: