Year	% of total energy
1971	51.024034926709646
1972	48.798429156099246
1973	44.63490772570008
1974	42.710521730481716
1975	41.059701803372825
1976	38.39061941155483
1977	37.752525813482194
1978	35.23484252543275
1979	34.69080800833994
1980	35.477382075997255
1981	36.81688447116674
1982	36.54820328306612
1983	38.91963380063476
1984	40.42331489415601
1985	39.119115477228945
1986	37.72443810228647
1987	37.94255966233641
1988	36.81716358795761
1989	36.428093934868734
1990	24.233752461638012
1991	23.352698299252577
1992	23.249244097606535
1993	22.60219217930805
1994	22.7133155237463
1995	21.46095151926477
1996	20.469954806966655
1997	19.75502502991105
1998	19.90898205598959
1999	20.423346497242942
2000	19.03602250288282
2001	19.407590287808514
2002	20.610195885484757
2003	21.673278793431933
2004	21.99105314105157
2005	22.086712813980604
2006	22.355516235076973
2007	22.848545238011248
2008	22.944303290700542
2009	23.74147147772679
2010	23.034083233220166
2011	21.967899961457494
2012	21.037268909691758
2013	20.544678288199705
2014	20.35314463747199