Year	% of total fuel combustion
1971	21.04752667313288
1972	17.40644038294169
1973	18.389830508474574
1974	20.982839313572544
1975	20.154539600772697
1976	18.205394190871367
1977	18.0466038671294
1978	16.600616468516073
1979	14.705882352941178
1980	15.440335493709492
1981	14.495049504950497
1982	12.297496318114874
1983	11.376673040152964
1984	9.709887507400829
1985	9.82613277133825
1986	11.37809187279152
1987	12.590909090909092
1988	12.10707767187183
1989	11.829537105069802
1990	11.796144302347775
1991	8.94627622780724
1992	7.214942009338755
1993	8.185336976320583
1994	7.854251012145749
1995	6.895101955013663
1996	10.404268417812437
1997	9.028811629739907
1998	9.181611518060114
1999	12.678600755460668
2000	12.400681044267877
2001	11.151258410166957
2002	11.929170549860206
2003	12.577260313353458
2004	14.301399945100194
2005	17.21120984278879
2006	16.2122969837587
2007	17.26676268202912
2008	16.952196739430782
2009	11.073642989230935
2010	10.1149647377065
2011	10.212919523637677
2012	9.329215173833848
2013	8.64097062957757
2014	6.4737999007303415