Year	% of total energy use
1971	1.7344919125865494
1972	1.6483287745530644
1973	1.9049190971246226
1974	1.7826333380053923
1975	2.037540074105727
1976	2.151595484036021
1977	2.0691249007479597
1978	2.512029799636065
1979	2.3733188810767207
1980	2.3653847601670632
1981	2.388077563846234
1982	2.1748712667430943
1983	2.35325952315435
1984	2.5206135763657733
1985	2.3844893749531515
1986	2.432572759680083
1987	2.1984347367899213
1988	2.439994160713866
1989	2.350637715008182
1990	2.052761772322742
1991	1.992244623500763
1992	2.0099478251847094
1993	1.8628291544809452
1994	2.0665259195658328
1995	1.9369385767340284
1996	1.8152653874702727
1997	1.8903924897601658
1998	2.019669591581681
1999	1.8981219000153777
2000	1.9865270745808947
2001	2.0967192602696003
2002	2.0119730145405255
2003	2.0837828430000993
2004	2.096979838245458
2005	2.267457922483113
2006	2.4169944290898577
2007	2.3459184369013473
2008	2.0718130287846024
2009	2.09481362884931
2010	2.43887071885112
2011	2.7501605693929543
2012	2.572838235612061
2013	2.8120427080835557
2014	2.7416590954869418