Year	% of total fuel combustion
1971	29.181742995968165
1972	29.346741009471405
1973	28.24801564477165
1974	28.397114720110576
1975	28.973209839657404
1976	29.178422616267124
1977	28.633682773587225
1978	28.50544543486783
1979	27.57696407298263
1980	27.412105998887704
1981	27.154204558212644
1982	28.267560806297396
1983	27.091081455553127
1984	26.856819781462377
1985	26.47160365958916
1986	27.223644833862952
1987	26.573057938371587
1988	26.128231208364262
1989	26.20613940300314
1990	25.024981324640798
1991	24.87547112634709
1992	25.119593071053906
1993	22.44943504058296
1994	21.417290494188745
1995	21.795530799353266
1996	20.713892906821446
1997	20.876196211976946
1998	20.60992790254413
1999	20.8642092140074
2000	20.24666189360936
2001	20.37824320100031
2002	20.303702246170612
2003	20.48576555110817
2004	20.29602265048049
2005	20.511879092929956
2006	21.686647532447743
2007	22.29150197041114
2008	22.001130777929063
2009	21.58885055733469
2010	22.302964464917114
2011	22.335645962685756
2012	21.14143523402769
2013	21.67846958174905
2014	21.68026177975244