Year % of total 1992 50.690398924249216 1993 32.31920590433483 1994 35.06693989071038 1995 29.09885077561722 1996 29.087174343734524 1997 28.0483227767925 1998 26.932294998730637 1999 30.16433728726147 2000 28.56795551112222 2001 42.84480371900827 2002 43.6231628638867 2003 49.697781013395456 2004 54.676916984452916 2005 50.60760163710778 2006 59.946918349429325 2007 63.95589240276263 2008 70.16639621365788 2009 74.79863166268895 2010 74.46363561076605 2011 66.66338935574228 2012 64.53013979193759 2013 63.50370181586493 2014 64.97883542752069 2015 68.2333291886851 2016 65.90719534598898