Year	% of total electricity output
1990	13.434182369362096
1991	13.77592747268046
1992	14.449044735236548
1993	14.888104269757308
1994	15.164026482451886
1995	14.838767173036606
1996	14.424492532286237
1997	14.818449618140065
1998	15.217448718903858
1999	15.150523994457552
2000	15.528920679474373
2001	16.179627378009943
2002	14.3675955311772
2003	14.183382160710291
2004	15.309796355647698
2005	15.330850379532903
2006	15.89475142481045
2007	16.790321909393
2008	18.21959611039014
2009	20.27256827358747
2010	22.105553733852286
2011	22.158489050302098
2012	25.009207527891924
2013	27.904969647875003
2014	29.579466323010262
2015	29.715352498589553