Year	% of total energy
1971	10.344912295994579
1972	10.685200973834766
1973	10.438798351213942
1974	10.689986158205562
1975	11.083522666392497
1976	10.350026195830765
1977	10.097892575427228
1978	9.715843543997497
1979	9.7538677363172
1980	9.642749315641309
1981	9.695605252481894
1982	9.251265759272034
1983	9.265549825600573
1984	9.451654813226451
1985	9.590620147031123
1986	9.36841073909037
1987	9.681123905909592
1988	9.821927521005154
1989	10.976054456937222
1990	8.480748463345995
1991	8.272237981319291
1992	9.003334768698467
1993	8.552654745048264
1994	8.441144079369165
1995	8.164386159451984
1996	8.11017308348966
1997	8.001236812827992
1998	8.178483911126095
1999	8.288122362896424
2000	8.487291889758609
2001	8.423420800288666
2002	8.701956124679807
2003	8.243253552195167
2004	7.64933041988055
2005	7.764989849183753
2006	7.929287858533321
2007	7.509619703363943
2008	7.071681680957191
2009	7.319837044852607
2010	7.544906310178556
2011	7.687436857043039
2012	7.9179852790748
2013	8.019394673210643
2014	7.7465729289681455