Year % of total 1990 0.5198833220620708 1991 0.5012237817433082 1992 0.6033601083739005 1993 0.5611404930766634 1994 0.5657055218291349 1995 0.5828825307483844 1996 0.6486283538796228 1997 0.667723445402848 1998 0.6578055417621449 1999 0.665636534961311 2000 0.6770108584273171 2001 0.46971110125318843 2002 0.7548987253716077 2003 0.6742522091672256 2004 0.5171939683092309 2005 0.4363691389542233 2006 0.1980055222144276 2007 0.2382726076408096 2008 0.33785380739414156 2009 0.2910402200447717 2010 0.3039212725390342 2011 0.5268074290537709 2012 0.4607252185772176 2013 0.5736135533790412 2014 0.675180228587304 2015 0.6528455624563368 2016 0.518660448963848