Year	% of total fuel combustion
1971	0
1972	0
1973	0
1974	0
1975	0
1976	0
1977	0
1978	0
1979	0
1980	0
1981	0
1982	0
1983	0
1984	0
1985	0
1986	0
1987	0
1988	0
1989	0
1990	0
1991	0
1992	4.400977995110025
1993	7.741935483870968
1994	8.807339449541285
1995	7.88690476190476
1996	6.619718309859156
1997	7.812499999999998
1998	10.051546391752577
1999	11.846689895470384
2000	6.681034482758622
2001	7.804878048780489
2002	6.0196560196560185
2003	6.725146198830409
2004	7.3
2005	6.906338694418164
2006	7.739307535641547
2007	7.352941176470589
2008	9.762532981530343
2009	10.526315789473683
2010	6.8354430379746836
2011	9.25925925925926
2012	15.384615384615385
2013	17.274758004467607
2014	14.621676891615543