Year	% of total fuel combustion
1971	2.804219192179059
1972	3.053435114503817
1973	3.1966813079551
1974	3.823178016726404
1975	4.240037071362373
1976	4.622425629290618
1977	5.019815059445179
1978	5.033557046979865
1979	5.993017843289371
1980	20.698924731182796
1981	19.88980716253444
1982	21.59348978046934
1983	21.31613882040584
1984	22.055321487451916
1985	21.565025716385012
1986	20.32488880293947
1987	21.449925261584454
1988	22.22017673048601
1989	22.60108067821874
1990	28.050337406529273
1991	24.671532846715326
1992	23.03571428571429
1993	23.256351039260974
1994	21.236757822123675
1995	20.378457059679768
1996	20.764362220058427
1997	20.287384315635652
1998	21.728145528044468
1999	21.838784445016742
2000	22.180043383947936
2001	17.93361884368308
2002	17.430197885605857
2003	14.839572192513373
2004	15.051090858878762
2005	15.946308724832214
2006	16.561557444474907
2007	15.77472681423368
2008	17.419536984754373
2009	19.938650306748464
2010	18.98148148148148
2011	15.616438356164386
2012	15.044814340588985
2013	16.803020767778477
2014	15.069894306171156