Year	% of energy use
1971	98.44658144037764
1972	98.77799479689958
1973	98.83342924739435
1974	99.30858702258078
1975	98.89208594877425
1976	98.79240408766951
1977	98.89122137671481
1978	98.9202931218428
1979	98.97685944780109
1980	99.27635375742064
1981	99.2912754333548
1982	99.30276449590613
1983	99.35481782172027
1984	99.28565412052845
1985	99.26769324459524
1986	99.35269356951912
1987	99.45103103893328
1988	99.50242010030972
1989	99.52187284741483
1990	99.55043981739227
1991	99.60232746108336
1992	99.64979693706229
1993	99.67518853793862
1994	99.39182379574511
1995	97.49624303700676
1996	97.71015780175998
1997	97.74582639673412
1998	97.82616175866347
1999	97.80270945308591
2000	97.92927818147103
2001	97.8969225275336
2002	97.91302327230784
2003	97.93737854854821
2004	97.70728562690235
2005	97.7009759238474
2006	97.76798265469014
2007	96.9921284320967
2008	96.86139637146252
2009	96.69790569053924
2010	96.35067157026708
2011	95.95964970511753
2012	95.19864627638434
2013	94.35630779462471
2014	94.0267505230889