10. The following data represents natural gas consumption from residential U.S. customers over a three yearperiod. source: http://www.eia.gov/dnav/ng/ng_cons_sum_dcu_nus_m.htm
a)Determine the monthly seasonal indexes.
b) Develop a monthly forecast for the next year.
c) Plot the usage and forecast on the same scatter plot.
year	Month	Usage
1	1	932,605
1	2	794,779
1	3	579,243
1	4	313,171
1	5	197,513
1	6	134,038
1	7	111,307
1	8	107,074
1	9	117,299
1	10	201,580
1	11	446,801
1	12	847,001
2	1	969,921
2	2	769,244
2	3	600,851
2	4	347,059
2	5	207,533
2	6	134,708
2	7	111,305
2	8	109,223
2	9	121,903
2	10	227,357
2	11	428,615
2	12	685,976
3	1	801,268
3	2	666,582
3	3	406,764
3	4	280,678
3	5	162,893
3	6	123,596
3	7	108,500
3	8	106,218
3	9	119,129
3	10	241,974
3	11	485,522
3	12	676,616