Year	% of energy use
1971	21.997565767495754
1972	21.975839464857614
1973	21.972327594302886
1974	21.794401167666372
1975	22.857369263811393
1976	20.36840047442537
1977	22.50647379345133
1978	21.984479190114584
1979	17.96231884206257
1980	17.855704868128953
1981	19.778173127015826
1982	21.04095641215119
1983	10.378781214090335
1984	15.059643021056829
1985	18.378723776774095
1986	16.18491809335173
1987	19.50204541817155
1988	14.762995336246936
1989	17.567215562845313
1990	16.999005676207286
1991	15.29810618845769
1992	14.734374187154422
1993	16.301499154794165
1994	17.072772293001613
1995	18.832460451434358
1996	19.169195118187844
1997	20.783857690814607
1998	26.79743856316343
1999	26.561077718706866
2000	28.96180687996844
2001	32.358632957194665
2002	36.56765650284782
2003	37.01525620705025
2004	36.772329080864836
2005	37.57713627792832
2006	42.45421777061835
2007	45.53118536108484
2008	42.05294380302354
2009	44.88279699340231
2010	45.90799648005504
2011	5.3068214860602705
2012	2.8754404314621573
2013	-7.4933499899135505
2014	-8.192103872768781