Year	% of total fuel combustion
1971	2.4726581074655245
1972	2.374031007751938
1973	2.1999999999999997
1974	2.030456852791878
1975	2.33781414377557
1976	2.124091671324762
1977	2.0353508302088907
1978	1.8059855521155828
1979	1.5033947623666337
1980	1.2149532710280377
1981	1.315171441991546
1982	1.3601741022850917
1983	1.420305102577591
1984	1.335972290945076
1985	1.8858307849133547
1986	2.8189910979228485
1987	1.51219512195122
1988	1.4919354838709677
1989	1.3
1990	1.393136255521576
1991	2.2292993630573243
1992	2.0890410958904115
1993	1.8410852713178296
1994	1.7063842306560741
1995	1.160280626011873
1996	1.841491841491841
1997	1.8008903278025092
1998	1.0782747603833858
1999	0.931204865070315
2000	1.1725982308167042
2001	1.0287183883411912
2002	1.223370596920481
2003	0.8847736625514397
2004	1.237577348584287
2005	0.6982726938625501
2006	0.5749191519942511
2007	0.6343165239454486
2008	0.6765899864681991
2009	0.7945162797943609
2010	1.2975652427467566
2011	1.5272244355909692
2012	1.1396011396011398
2013	0.8169735398122177
2014	0.7914523149980212