Year	% of energy use
1971	9.762031650883639
1972	9.232099671239311
1973	9.831581034355267
1974	9.081814990584943
1975	7.295552194540064
1976	8.573584314200579
1977	8.777171118613785
1978	7.48405502656035
1979	9.902650727697374
1980	9.463231669353148
1981	7.8095656622036405
1982	6.552875035961955
1983	4.815674411812474
1984	4.000558120089358
1985	6.315665434589389
1986	5.300916204876261
1987	5.947143571350007
1988	6.184235008025658
1989	7.615272912872091
1990	8.259887793064307
1991	8.797442832026059
1992	11.04552069437521
1993	11.984993226903127
1994	12.197368852824757
1995	13.055077485055788
1996	14.256988899669976
1997	14.934121714559002
1998	17.230376255376502
1999	20.062413222318423
2000	20.44553976683605
2001	20.080460840312927
2002	20.352775500250036
2003	19.66334599544582
2004	21.380638358336224
2005	22.052652629406573
2006	23.469241708485722
2007	24.969607228614123
2008	25.793979456804788
2009	27.45267630128473
2010	28.3476087460204
2011	29.382041992503634
2012	31.496522282074856
2013	32.47555404147748
2014	34.305523751201925