Year	% of energy use
1971	48.21823392667857
1972	54.35042358302766
1973	57.87714310630505
1974	58.73216888722983
1975	59.220236269416596
1976	58.1230835043254
1977	59.84191832047502
1978	59.409010767301176
1979	59.717805846689046
1980	61.368555471898524
1981	56.2235312955802
1982	52.28415526435452
1983	58.709761196675935
1984	58.141887643468905
1985	67.65281185145989
1986	68.75879384691012
1987	72.39352349830142
1988	75.61270574803827
1989	78.53946201486134
1990	76.45631321874151
1991	76.17839988573931
1992	78.78107051563151
1993	81.03756103841167
1994	83.56493018068598
1995	84.91800504478792
1996	85.56770280734254
1997	87.17742175639903
1998	86.07321976923241
1999	86.11172966487948
2000	87.44478290185553
2001	87.33238101930164
2002	87.38857353806665
2003	86.6482989975183
2004	84.29269728361584
2005	85.34725044289382
2006	85.94508865232623
2007	86.05524951720503
2008	86.5832296088198
2009	86.28308308274781
2010	86.91857948083504
2011	87.170577873891
2012	87.23523702719321
2013	86.5939353448417
2014	86.7171002235763