Year	% of total energy
1971	66.42292460770898
1972	66.85053628132428
1973	64.86576761613888
1974	62.85523092129566
1975	62.04850877640266
1976	60.79027856944173
1977	59.589550969367416
1978	58.03408083406409
1979	56.50284684426321
1980	54.95406261040189
1981	53.914522052134345
1982	53.63419791594221
1983	52.34513512729378
1984	52.72005968489553
1985	52.49458958706689
1986	52.159221905033
1987	52.02813479833182
1988	52.012063240258954
1989	51.53794663837487
1990	40.76241248455734
1991	41.00991169251245
1992	40.893515811859984
1993	41.319143698468544
1994	40.86322702126723
1995	41.599013044545615
1996	41.5570645554943
1997	40.943989027524324
1998	42.78717494069843
1999	44.26843762990035
2000	43.852824510705695
2001	43.14683598589893
2002	43.08218521466238
2003	43.89713001722908
2004	43.46896391161575
2005	43.33804318895075
2006	43.20791259022679
2007	44.16020093254655
2008	43.21737161635923
2009	43.62331044642339
2010	42.39084748649527
2011	43.74679739964713
2012	41.621629487227615
2013	42.13877773402857
2014	50.016961538508184