Year	% of total energy use
1971	0.5389875628968045
1972	0.47287961692305347
1973	0.2919178460755667
1974	0.38424507306039923
1975	0.4200995993280495
1976	0.3889877806026679
1977	0.39461348800183876
1978	0.40060597222897326
1979	0.38704809493284
1980	0.45293890196550035
1981	0.46295100040481296
1982	0.5072549250914238
1983	0.6444943941477911
1984	0.6430069998041071
1985	0.7480646003073443
1986	0.7362038816777687
1987	0.5974555618110851
1988	0.47348257719303216
1989	0.4747108466777848
1990	0.18243862813745343
1991	0.23151505307367198
1992	0.22600628318376528
1993	0.20983300789788126
1994	0.22622446517212014
1995	0.22929731586590257
1996	0.2311750069412981
1997	0.2493252586029602
1998	0.2511211543588567
1999	0.24880177422464356
2000	0.23685959533127804
2001	0.12324125995696969
2002	0.20610127991782692
2003	0.24692631387468242
2004	0.34058425199112724
2005	0.40635517602505683
2006	0.39847275003052285
2007	0.38651614155182396
2008	0.37047180971397176
2009	0.405246569876504
2010	0.48290262694743485
2011	0.5129957449105982
2012	0.6259032775325116
2013	0.5284905301095466
2014	0.569707729933871