Year	% of total energy use
1971	5.5585273337490975
1972	5.158188484997652
1973	5.537133796251318
1974	5.87028622233481
1975	5.96342797128968
1976	6.034361221738564
1977	6.240695852097543
1978	6.244502598629905
1979	5.791312224423014
1980	5.583892471616674
1981	4.994312615578294
1982	4.676034371264454
1983	3.9497920148855328
1984	3.495298798265578
1985	2.903935119003699
1986	3.0286759758466655
1987	2.6516644002868373
1988	2.691826737615893
1989	2.7976678121560865
1990	2.269015784645259
1991	2.261944451821675
1992	2.1514983987883833
1993	2.239674015168116
1994	2.465784994742276
1995	2.3940703626192645
1996	2.3751974125006874
1997	2.3913302967609904
1998	2.2679632812594632
1999	2.6353114977301275
2000	2.4249874678948733
2001	2.4054248729912286
2002	1.9855641818844059
2003	1.9735155787140295
2004	1.8027134231924715
2005	1.5639883979688247
2006	1.5292340522872465
2007	1.7205957208792837
2008	1.581923410589785
2009	1.392265299940126
2010	1.4944653604923694
2011	1.4579186127784023
2012	1.3723771962583051
2013	1.4659445453042153
2014	1.4997177283421455