Year	% of energy use
1971	69.97779179796134
1972	71.1585577944266
1973	73.30283935689516
1974	75.89262764147611
1975	73.59235086890892
1976	73.88949019027785
1977	74.76454066248992
1978	75.24369025035588
1979	74.07037147332294
1980	72.74581902654005
1981	69.88165833402124
1982	68.29851507161744
1983	67.9799589087928
1984	67.24258611635628
1985	68.90046202738252
1986	68.05547082262653
1987	67.18308341255484
1988	66.48414248708573
1989	66.6625707943264
1990	65.93959377237444
1991	61.22515794454845
1992	56.92079016552151
1993	57.72537565533413
1994	55.716470536258974
1995	55.426377254335925
1996	53.472050107362655
1997	50.96275959985084
1998	49.29183811962136
1999	50.103425515310775
2000	46.8405214353187
2001	46.58430532006188
2002	43.87409364993301
2003	47.3995192266974
2004	45.46866217923404
2005	46.48048214187172
2006	46.05108552462746
2007	50.42872314322538
2008	48.292006599754785
2009	43.787234898149634
2010	40.74864321677206
2011	35.66361961933938
2012	35.867295499559944
2013	37.14267985198577
2014	36.550777724681865