Year	% of total fuel combustion
1971	12.400937604643374
1972	13.047722342733188
1973	13.566257475605918
1974	13.707663103207116
1975	14.065848431716345
1976	13.639665819106426
1977	13.688673531193215
1978	13.824846574888042
1979	13.513720094779488
1980	13.990875515967849
1981	14.619595732734417
1982	14.967982924226256
1983	15.14750378214826
1984	15.643140849373662
1985	15.095243800167722
1986	14.915600408482012
1987	15.547961923358555
1988	15.917980324759984
1989	17.225910640588552
1990	16.337413646830687
1991	16.418927288492505
1992	17.541587128442874
1993	17.57300739222718
1994	19.95290900805104
1995	20.943177425589486
1996	23.078793774319067
1997	23.834238910064066
1998	23.2107682206172
1999	24.99804519508953
2000	25.507332247074512
2001	25.51899449230335
2002	26.66194690265487
2003	27.109049989770178
2004	26.553598323619934
2005	26.24453115762091
2006	26.58687390095865
2007	28.2815096131023
2008	28.32955237094008
2009	29.388231371895316
2010	28.766966382223238
2011	29.61695847588381
2012	27.662840850939393
2013	25.0968992248062
2014	23.417021948523608