Year	% of total energy
1971	69.0634933228159
1972	67.06888911431334
1973	65.12257822693857
1974	66.4037037457889
1975	61.63828004222819
1976	54.64749693280682
1977	54.99939474639874
1978	53.33169208842803
1979	55.879820147312365
1980	55.90145750974413
1981	52.00966446622232
1982	51.36616357105858
1983	55.305606314029234
1984	55.24609614095956
1985	58.85780130790881
1986	53.706133856315816
1987	52.1945467955583
1988	48.87541167626823
1989	47.3884038670218
1990	47.856391452867506
1991	45.46311947101534
1992	45.12217288475255
1993	42.41011644710592
1994	40.12500332405132
1995	37.891193931202025
1996	39.862176301065126
1997	36.58032858687825
1998	36.06950838548953
1999	35.02787864147695
2000	33.6747300003655
2001	32.45836902219155
2002	32.23955541817556
2003	29.05544988816749
2004	29.631058805216547
2005	29.65809723726166
2006	28.791131232328947
2007	15.506614810666655
2008	15.942114552215244
2009	11.116348383874495
2010	11.150419074661686
2011	11.106263606530483
2012	9.072452227414972
2013	8.969151632540399
2014	9.539495272111237