Year	% of total fuel combustion
1971	31.57894736842105
1972	23.076923076923077
1973	17.94871794871795
1974	16.216216216216218
1975	21.875000000000004
1976	33.333333333333336
1977	31.03448275862069
1978	35.714285714285715
1979	24.444444444444443
1980	30.76923076923077
1981	34.090909090909086
1982	33.333333333333336
1983	24.65753424657534
1984	26.582278481012654
1985	38.18181818181818
1986	32.432432432432435
1987	32
1988	31.08108108108108
1989	43.10344827586207
1990	38.20224719101124
1991	35.39823008849558
1992	38.59649122807018
1993	36.92307692307692
1994	34.567901234567906
1995	35.22727272727273
1996	34.97267759562842
1997	35.238095238095234
1998	35
1999	25.581395348837212
2000	26.774193548387093
2001	22.388059701492537
2002	29.588014981273407
2003	26.896551724137936
2004	31.111111111111107
2005	27.36156351791531
2006	35.199999999999996
2007	35.27131782945737
2008	46.527777777777786
2009	51.02040816326531
2010	47.08737864077669
2011	44.54545454545455
2012	43.460764587525155
2013	48.76543209876543
2014	44.01349072512647