Year	% of total energy
1971	62.65572637764906
1972	62.51475885137323
1973	61.226489594489564
1974	61.03912770524449
1975	60.837918959479744
1976	60.049788632881665
1977	59.68207284883542
1978	58.770781814613066
1979	58.599099410781506
1980	57.77753360800968
1981	56.495759369153774
1982	55.327416026458714
1983	55.73609359469599
1984	55.24728076186779
1985	55.57162077991461
1986	55.26748366071198
1987	54.99198869148073
1988	54.77208336554641
1989	56.24085760916623
1990	48.688143583152076
1991	48.173110071434884
1992	49.61164484758526
1993	49.20187439791767
1994	49.78950102156719
1995	49.200807058944385
1996	49.04224506709069
1997	48.971099564376445
1998	49.95944097270808
1999	49.77169672208333
2000	50.42465655825514
2001	49.98306252938217
2002	50.547577056401686
2003	49.739744746998014
2004	48.57503199438155
2005	48.921466790204754
2006	49.46182735176865
2007	48.64001247353078
2008	47.858382942822985
2009	48.98989553378173
2010	48.94391180789522
2011	49.00274310796878
2012	47.89886724515343
2013	48.449488467736685
2014	47.16266828133586