Year	% of total fuel combustion
1971	3.8461538461538463
1972	11.538461538461538
1973	13.793103448275865
1974	20
1975	19.444444444444446
1976	22.32142857142857
1977	29.00763358778626
1978	33.5483870967742
1979	35.97883597883598
1980	40.88888888888889
1981	47.808764940239044
1982	50
1983	55.012853470437015
1984	46.787148594377506
1985	43.51687388987567
1986	56.661316211878
1987	57.68621236133122
1988	54.29864253393665
1989	54.09356725146199
1990	56.496062992125985
1991	41.702127659574465
1992	45.3183520599251
1993	51.669316375198726
1994	56.8
1995	57.658270932607216
1996	59.27662424648359
1997	62.88384512683578
1998	64.96398166339227
1999	61.61327231121281
2000	65.06614404703576
2001	62.71186440677966
2002	60.76205918119172
2003	60.526315789473685
2004	65.35714285714286
2005	61.92214111922141
2006	50.539623805118715
2007	45.69936795823028
2008	48.44144903117102
2009	48.5974025974026
2010	45.34938621340888
2011	41.764102564102565
2012	39.37051352843733
2013	38.54461756373938
2014	38.530884808013354