Year	% of total fuel combustion
1960	2.845982142857143
1961	2.710027100271003
1962	2.715578847070034
1963	2.2753128555176336
1964	2.176493866244559
1965	2.314474650991918
1966	2.6441424899008448
1967	2.9640084685956247
1968	3.465184700882642
1969	3.4678624813153958
1970	4.451038575667655
1971	5.165767154973015
1972	5.689611379222759
1973	5.23621131021643
1974	5.092231748506105
1975	5.389221556886227
1976	5.2631578947368425
1977	4.797331965110314
1978	4.638403990024938
1979	4.865424430641823
1980	3.210191082802548
1981	3.087757313109426
1982	3.263670197537934
1983	2.944188428059395
1984	2.906071613907629
1985	2.8256704980842913
1986	2.976476236197792
1987	3.049237690577356
1988	2.7345709984947315
1989	2.5848960973137354
1990	6.059862610402356
1991	6.8616163941975605
1992	7.1543224031185515
1993	6.68912415784408
1994	7.308641975308642
1995	6.824210272486135
1996	6.890835898650249
1997	7.555879494655006
1998	8.466228893058162
1999	7.919869555089681
2000	7.749165474487363
2001	7.839520405810468
2002	8.343294286397322
2003	8.107482047718323
2004	8.927749654855038
2005	9.088838268792712
2006	9.3836246550138
2007	9.005538165181797
2008	8.976744186046512
2009	8.585131894484412
2010	8.677494199535964
2011	9.130434782608695
2012	8.711747285291214
2013	8.760529482551144
2014	9.30047694753577