Year	% of total electricity output
1990	83.05555322993261
1991	84.10579005481576
1992	82.05264878598942
1993	81.66080392125926
1994	78.64368169343363
1995	77.1683059311294
1996	76.25561454379466
1997	74.41077272385196
1998	71.89828098563503
1999	73.46873079275838
2000	74.69294725086883
2001	73.85276920870291
2002	71.60231023148178
2003	70.07682001802925
2004	69.86023156979506
2005	68.75817508668457
2006	67.03885572552622
2007	65.86914334537731
2008	66.48840729851527
2009	68.45867105935034
2010	69.20818944796723
2011	68.1845271117751
2012	67.28142712813907
2013	67.67199387816643
2014	67.04826055380323
2015	63.42129178034234