Year Percent 1990 0.68597 1991 0.6768 1992 0.66708 1993 0.63719 1994 0.61273 1995 1.18212 1996 1.18832 1997 1.05444 1998 0.99571 1999 0.96602 2000 0.95101 2001 1.26798 2002 1.46916 2003 0.93423 2006 0.50558 2007 0.48779 2008 0.48103 2009 0.46679 2010 0.47557 2011 0.45597 2012 0.42207 2013 0.41931 2014 0.40919 2015 0.41173 2016 0.44082 2017 0.42822 2018 0.40655 2019 0.38862 2020 0.40708