Year	% of total energy use
1960	3.7112028139561177
1961	3.6394372044537806
1962	3.3646740260395576
1963	3.4328539267992024
1964	3.239459117870878
1965	3.4675621394357
1966	3.660837662384515
1967	3.470426847723704
1968	3.317356660205227
1969	3.1740566744948073
1970	2.87504509696602
1971	2.681370753361855
1972	2.934414005658388
1973	2.8696176126318176
1974	3.1838605932897837
1975	3.974291249265323
1976	3.7569579370326442
1977	4.7205384091993485
1978	4.928344598077222
1979	5.153240540178723
1980	5.775572952378669
1981	7.58103207902103
1982	8.199389997606207
1983	9.329345594590722
1984	11.26064367486494
1985	12.702569953231956
1986	13.464051555139587
1987	13.840271300291187
1988	14.682095214113227
1989	14.860350258902056
1990	14.835552228298338
1991	15.314080937527505
1992	15.806569625115564
1993	16.315470513313926
1994	16.42703166611342
1995	16.258649032251043
1996	16.483899208847365
1997	16.79231760044635
1998	16.66401132011372
1999	17.122703629665384
2000	17.36904461290798
2001	17.549211679862324
2002	17.554968441525773
2003	17.313991315114063
2004	17.599154525536786
2005	17.335122228075274
2006	17.32575561452078
2007	17.059519211695985
2008	17.485342958175583
2009	17.668313280486046
2010	17.895365474481096
2011	18.284576238938882
2012	18.522220567420177
2013	19.134649029662548
2014	20.161456059774785
2015	19.77816620648339