Year	% of total energy
1971	62.65572637764906
1972	62.514758851373244
1973	61.226489594489564
1974	61.03912770524449
1975	60.83791895947975
1976	60.049788632881665
1977	59.682072848835425
1978	58.77078181461308
1979	58.59909941078149
1980	57.77753360800971
1981	56.495759369153745
1982	55.327416026458714
1983	55.736093594695966
1984	55.2472807618678
1985	55.57162077991462
1986	55.267483660711974
1987	54.99198869148072
1988	54.77208336554641
1989	56.24085760916621
1990	48.68814358315209
1991	48.17311007143489
1992	49.61164484758523
1993	49.201874397917685
1994	49.7895010215672
1995	49.20080705894438
1996	49.04224506709069
1997	48.97109956437642
1998	49.95944097270807
1999	49.77169672208332
2000	50.42465655825514
2001	49.98306252938219
2002	50.547577056401664
2003	49.739744746998014
2004	48.57503199438156
2005	48.92146679020475
2006	49.46182735176864
2007	48.64001247353077
2008	47.85838294282299
2009	48.98989553378173
2010	48.94391180789523
2011	49.00274310796877
2012	47.89886724515343
2013	48.44948846773668
2014	47.16266828133587