Year	% of total fuel combustion
1971	2.60707635009311
1972	2.5594149908592327
1973	3.1746031746031744
1974	2.697495183044316
1975	3.282275711159737
1976	3.2818532818532824
1977	2.861952861952862
1978	3.061224489795918
1979	3.0405405405405403
1980	2.6687598116169546
1981	2.5
1982	2.564102564102564
1983	2.710843373493976
1984	2.9629629629629632
1985	2.556390977443609
1986	2.781844802342606
1987	1.8105849582172702
1988	2.979274611398964
1989	1.8445322793148884
1990	1.7721518987341773
1991	1.920614596670935
1992	2.4479804161566707
1993	2.41423125794155
1994	2.2332506203473943
1995	1.8382352941176474
1996	1.76678445229682
1997	1.9758507135016465
1998	1.8987341772151896
1999	1.8987341772151896
2000	4.851485148514851
2001	3.993203058623619
2002	3.9816232771822357
2003	2.939255388634879
2004	2.857142857142857
2005	2.394526795895097
2006	2.314814814814815
2007	2.032332563510393
2008	2.1365536460752437
2009	2.379771938522558
2010	1.880035810205909
2011	1.70863309352518
2012	1.4972776769509983
2013	2.3093681917211333
2014	1.680310211115898