Year	% of total energy use
1971	10.941408120908944
1972	10.942870585617637
1973	10.358455422305195
1974	11.685151535276576
1975	11.192053712210363
1976	12.417219532901935
1977	9.842107876117254
1978	10.054684230801787
1979	10.687884491395511
1980	14.507572472215436
1981	16.652740655872737
1982	17.841098614390763
1983	21.167463404679008
1984	21.03941265814538
1985	18.75264556648551
1986	18.764594626007757
1987	18.273326467850985
1988	18.11102123217113
1989	17.774642219246754
1990	16.50915523898719
1991	15.580285344438177
1992	11.273827248596668
1993	12.769538606925032
1994	14.046198641580517
1995	13.048533007231253
1996	14.599603729387129
1997	16.301406084538574
1998	16.929231342961142
1999	17.38631314424313
2000	17.028333154694625
2001	17.61905690316675
2002	17.539060085255485
2003	17.187289647131053
2004	15.410947409960057
2005	15.739131822674675
2006	14.96695003186932
2007	14.319860852461112
2008	14.509559393055518
2009	14.710178925055207
2010	14.551908020861381
2011	14.39198692844717
2012	14.766538569307603
2013	13.989058187017134
2014	14.208709727985605