Year	% of total energy use
1971	3.5044457561860454
1972	3.986335213709285
1973	5.532737638222825
1974	6.123031305777501
1975	6.919162459520887
1976	7.459715709047349
1977	8.148727192070064
1978	7.956728350586404
1979	10.263759161465904
1980	8.259654631185422
1981	9.727009602779782
1982	9.985082750792769
1983	9.675467521614229
1984	7.964705003224036
1985	6.741081811517616
1986	11.986751784733663
1987	10.134538549589589
1988	8.669958511775008
1989	9.14789279975118
1990	4.676392164169472
1991	5.3995564778602345
1992	8.468053362077407
1993	10.012654626878009
1994	10.686573877482383
1995	12.311927784886159
1996	16.02528939949253
1997	14.372317442908193
1998	13.875295267774874
1999	20.236479742656847
2000	19.677698581947887
2001	18.295069799505946
2002	17.93678489512184
2003	18.7811504312036
2004	20.682114701530722
2005	20.33206363211398
2006	14.006447140135487
2007	15.54963185933446
2008	19.268817676540806
2009	21.87501519447765
2010	23.282191877561743
2011	22.10933619452633
2012	25.419173756688014
2013	26.068785011922806
2014	24.548050209935894