Year Percent 1994 39.96385 1995 46.29051 1996 63.94773 1997 55.68139 1998 45.50012 1999 37.15205 2000 40.07158 2001 48.43285 2002 50.97053 2003 57.7699 2004 63.77377 2005 58.81527 2006 57.68332 2007 64.40112 2008 66.24499 2009 58.64788 2010 51.82573 2011 51.67383 2012 44.85474 2013 43.5739 2014 38.84753 2015 32.88303 2016 30.56619 2017 46.18446