Year % of total energy 1990 0.6281130316370394 1991 0.7551130997087925 1992 0.9107731266201204 1993 1.0215139742829564 1994 1.2198557816425144 1995 1.3093888423657172 1996 1.5205616642774054 1997 1.5750659765235957 1998 1.646702774347147 1999 1.8663380001412242 2000 2.0658475240319496 2001 1.9740418202376555 2002 2.24020322960371 2003 2.395064160732031 2004 2.2046843525803035 2005 1.859842244548115 2006 2.2480840360099674 2007 1.8947256942831034 2008 2.1195093199492474 2009 2.2056785554434324 2010 4.807830885424285 2011 6.130717040817952 2012 6.534627894346208 2013 8.591704969597625 2014 8.329096687684213