Question: The following data shows residential and commercial natural gas consumption (quadrillion Btu) from 1982 through 1997.

Year Consumption Year Consumption

1982 25.6 1990 29.4

1983 25.6 1991 30.1

1984 26.5 1992 30.0

1985 26.7 1993 31.1

1986 26.9 1994 31.4

1987 27.6 1995 32.3

1988 28.9 1996 33.7

1989 29.4 1997 33.7

For the data above, determine the centered moving average for N = 2; for N = 4.