Year	% of energy use
1971	14.729219883402154
1972	14.267648022885066
1973	15.904799412681752
1974	16.554618237280135
1975	18.909957911670837
1976	19.170958531854374
1977	17.77304222081694
1978	18.49855792259547
1979	18.696706633926972
1980	19.7245039525153
1981	19.778924697172574
1982	19.0643915326683
1983	16.1129143115898
1984	15.264645321666997
1985	15.405365642770297
1986	15.983675141165785
1987	16.2803614983114
1988	14.760753176508029
1989	15.462557680044878
1990	15.529171645935488
1991	13.60581250383794
1992	14.240146640889412
1993	14.554455183732301
1994	14.777146674936208
1995	19.655404422072607
1996	18.954217227537118
1997	21.594699019783803
1998	21.33620505295199
1999	18.185585538624377
2000	17.00741810441528
2001	18.820144540340795
2002	18.058807421250098
2003	18.470235220475313
2004	16.02871433514164
2005	15.04735419769384
2006	13.724553401097852
2007	13.634140163355946
2008	12.821796582200506
2009	12.358457600591748
2010	14.528703579378496
2011	16.93574126102663
2012	17.7915866489742
2013	14.978323771415555
2014	16.841702642624494