Year	% of total fuel combustion
1971	15.087564222971109
1972	14.035274118147045
1973	14.18390682337925
1974	12.503687678237782
1975	12.20927554921015
1976	12.336263357462943
1977	12.6025543432293
1978	13.587027592519943
1979	13.698245050399581
1980	12.617357453629497
1981	12.998056365403304
1982	12.277562705358012
1983	12.349177330895795
1984	12.93669336893636
1985	11.790532449908198
1986	10.51310788422181
1987	10.331185712670962
1988	10.832226838565981
1989	10.385573378499553
1990	10.75017439339379
1991	10.502490605610419
1992	9.98170189192365
1993	9.674979887369267
1994	9.898968349511605
1995	9.567883789283293
1996	9.399643513017176
1997	9.682830326388977
1998	9.203234419870016
1999	8.981336572376257
2000	8.569920488747137
2001	8.31289631249862
2002	8.393903116849803
2003	8.450925712368692
2004	8.029992122691512
2005	7.806739658015155
2006	7.464891546162403
2007	6.926105725896993
2008	6.596951251235626
2009	6.272677404217915
2010	6.208523076537078
2011	6.173230416288296
2012	5.7014898702227
2013	5.704306705677856
2014	5.490005793025593