Year	% of total energy use
1990	7.245315088519087
1991	8.159335903285713
1992	11.644413170808612
1993	14.560898914435056
1994	23.058538281360438
1995	25.794644959556074
1996	21.29588382694454
1997	20.86017051144565
1998	19.36174663916301
1999	25.96703106120427
2000	25.59701552655877
2001	23.6197034402545
2002	20.121167003175156
2003	23.051659227295698
2004	20.269670033484562
2005	19.50686415334351
2006	20.00667329883029
2007	18.389419991664298
2008	16.54746192098
2009	18.832886675960136
2010	20.295193618318713
2011	21.111613484202344
2012	18.652312607165943
2013	20.904031642657003
2014	22.7125830672669