Year	% of total energy
1971	62.65572637764907
1972	62.514758851373244
1973	61.226489594489536
1974	61.039127705244475
1975	60.83791895947974
1976	60.04978863288168
1977	59.68207284883544
1978	58.77078181461306
1979	58.59909941078149
1980	57.777533608009705
1981	56.49575936915378
1982	55.32741602645872
1983	55.736093594695966
1984	55.24728076186778
1985	55.57162077991462
1986	55.267483660711974
1987	54.99198869148072
1988	54.7720833655464
1989	56.24085760916621
1990	48.68814358315209
1991	48.17311007143489
1992	49.61164484758523
1993	49.20187439791767
1994	49.78950102156718
1995	49.20080705894438
1996	49.04224506709069
1997	48.97109956437643
1998	49.95944097270808
1999	49.77169672208332
2000	50.42465655825514
2001	49.98306252938218
2002	50.547577056401664
2003	49.73974474699804
2004	48.575031994381554
2005	48.92146679020474
2006	49.46182735176864
2007	48.640012473530774
2008	47.858382942822985
2009	48.98989553378173
2010	48.94391180789523
2011	49.00274310796876
2012	47.898867245153426
2013	48.449488467736685
2014	47.162668281335854