Year	% of total energy
1971	1.3989154138777633
1972	1.3041253502118664
1973	1.16611610085175
1974	1.1107890230582875
1975	1.0185941069618027
1976	1.0325967132382885
1977	0.9084731374451387
1978	0.7901874973861069
1979	0.7192552719519932
1980	0.6918654095228689
1981	1.4329970499321074
1982	1.3722027593226447
1983	1.3417407669252293
1984	1.3271887311782244
1985	1.3466245084642363
1986	1.3196750249384377
1987	0.6890407426137748
1988	0.6052713903163408
1989	0.5962748599892114
1990	0.6109549486936307
1991	0.5234631831716524
1992	0.7339409044782124
1993	0.6114079203637944
1994	0.7253362040846636
1995	0.8480224480636025
1996	0.932552679123391
1997	1.1249066633458948
1998	2.0394628816157985
1999	2.3002369682349215
2000	2.939039328647082
2001	2.7835167498079167
2002	3.382983627284349
2003	3.5197577913926414
2004	3.763333359172405
2005	3.472851174038737
2006	3.634605395972695
2007	3.37448092411921
2008	3.817760290602041
2009	4.258573007389945
2010	5.051826212684369
2011	4.990404759604471
2012	5.9394268606535645
2013	6.632528631737015
2014	5.996296943156295