SSE	ASSOCIATED BRITISH FOODS	CENTRICA
2010	5,323.42	3,845.56	9,912.27
2011	5,422.08	3,942.54	9,551.09
2012	5,468.10	3,158.78	9,750.19
2013	5,682.36	3,736.70	9,106.88
2014	5,439.05	4,037.54	8,614.21
2015	5,476.74	4,096.91	9,096.93
2016	5,995.45	4,955.88	8,833.80
2017	5,796.25	4,710.46	7,995.02
2018	5,264.52	4,362.12	7,007.82
2019	5,402.15	4,057.33	6,297.41
2020	5,616.68	4,508.58	7,690.92
2021	5,530.80	4,112.75	7,661.95

Here is the market capitalization during 2010-2021(in million), how to calculate the market weight of each companies?(based on each year, the sum or the final year?)