Year	% of total fuel combustion
1971	17.597157855182704
1972	18.04013435166763
1973	19.041144901610014
1974	18.583689265876597
1975	18.91205849483232
1976	18.999557178306752
1977	19.28897624994458
1978	22.27487219819111
1979	23.56812135475289
1980	26.254936418284036
1981	25.911491318666332
1982	25.67125941200362
1983	25.604568844998365
1984	25.73132585853691
1985	28.100412342124912
1986	28.572310986657886
1987	29.69558994457412
1988	30.76419184784787
1989	33.032596291624834
1990	35.09056994818653
1991	36.6938972024441
1992	38.42253858654545
1993	39.79723603593703
1994	41.156279533760376
1995	40.39040622400319
1996	44.72972266892696
1997	44.35697400198086
1998	45.90363512608669
1999	47.35625313657714
2000	48.86392490491502
2001	49.07498036065215
2002	50.45007445910441
2003	51.56965736906388
2004	48.720329586124215
2005	49.001918674616306
2006	50.24188249990425
2007	50.19086266136786
2008	49.288527825320955
2009	49.426476248506475
2010	50.64392780491606
2011	51.61494510124014
2012	51.69881506358423
2013	52.25693756390644
2014	51.50340250643355