Year Percent 1995 47.85652 1996 47.43845 1997 48.73227 1998 49.23423 1999 48.48139 2000 53.67352 2001 52.78977 2002 51.16958 2003 51.21262 2004 56.41087 2005 60.21754 2006 64.74323 2007 68.8949 2008 68.03552 2009 55.37386 2010 62.85322 2011 68.53835 2012 68.90662 2013 68.95777 2014 68.41448 2015 68.40446 2016 68.49812 2017 72.55322