Year	% of total fuel combustion
1971	23.020257826887665
1972	27.042801556420237
1973	27.58620689655173
1974	17.76504297994269
1975	14.164648910411623
1976	12.486544671689991
1977	8.05168986083499
1978	11.527093596059112
1979	11.327831957989497
1980	20.86038961038961
1981	25.613275613275615
1982	26.94394213381555
1983	27.826086956521735
1984	29.31034482758621
1985	26.779313876088068
1986	24.70195517405818
1987	22.992854140395124
1988	25.37863282848956
1989	28.295549958018473
1990	29.20646583394563
1991	26.964405641370043
1992	29.773691654879777
1993	30.714791224345362
1994	35.59033684926846
1995	36.92159383033419
1996	36.955886649138186
1997	39.2060272384816
1998	39.17910447761194
1999	43.052516411378555
2000	43.988111321264526
2001	43.91874517870919
2002	47.23618090452262
2003	50.799600199900055
2004	47.71657250470811
2005	43.49859681945743
2006	43.74448561849303
2007	44.436986071488505
2008	45.745027714378864
2009	52.13554535827745
2010	52.27882037533512
2011	51.491819056785374
2012	52.971845672575604
2013	48.328877005347586
2014	44.468625317373956