Year	% of total energy use
1965	0.04454393741473203
1966	0.05835232837324971
1967	0.046763262112858604
1968	0.04952279795656021
1969	0.04934036402318067
1970	0.04231178913342906
1971	0.04336493398823348
1972	0.04837696311517369
1973	0.040827666962995494
1974	0.03162606747057836
1975	0.061194829704803264
1976	0.05792929115612821
1977	0.04954711983682781
1978	0.0415373902311114
1979	0.04446215470698091
1980	0.033981437287084616
1981	0.051283835156261656
1982	0.048551898958363995
1983	2.3719627311987477
1984	3.464713737535341
1985	5.720202665841085
1986	6.57332774753072
1987	9.36640499362445
1988	11.593422676032265
1989	12.058422670850225
1990	12.807786600678531
1991	13.453447115896491
1992	14.91460992565142
1993	14.406109656189898
1994	15.141265421059025
1995	14.549578356756927
1996	14.40977865480442
1997	14.490535914683807
1998	14.629090173156637
1999	14.902502695720907
2000	15.281519020205304
2001	14.882295033538865
2002	14.693252428661562
2003	11.459505001196417
2004	12.398885634653942
2005	13.57771928630481
2006	13.359428400185374
2007	14.879933400250344
2008	15.241017572874094
2009	16.95756368706775
2010	16.815559946186678
2011	17.345289217031475
2012	18.614338495059624
2013	19.084424124510154
2014	19.048966914164343
2015	18.451463435270316