Year Percent 1992 0.50953 1993 0.50612 1994 0.23868 1995 0.48458 1996 0.52115 1997 0.95332 1998 1.08392 1999 1.00038 2000 0.82192 2001 0.731 2002 0.71411 2003 0.69858 2004 0.71552 2005 0.85349 2006 0.80273 2007 0.79086 2008 0.77814 2009 0.76452 2010 0.74117 2011 0.56278 2012 0.55457 2013 0.54719 2014 0.54007 2015 0.5337 2016 0.52697 2017 0.51999 2018 0.51413 2019 0.50853 2020 0.50854