Year Percent 1990 0.30593 1991 1.56155 1992 1.59837 1993 1.56542 1994 1.5271 1995 3.33708 1996 3.10879 1997 3.09887 1998 2.84781 1999 2.8 2000 2.66542 2001 2.72448 2002 3.17616 2003 3.07934 2004 3.03304 2005 2.52118 2006 2.6662 2007 2.6464 2008 2.62786 2009 2.73535 2010 2.71953 2011 2.71255 2012 2.70458 2013 2.63446 2014 2.64239 2015 3.08732 2016 3.52408 2017 3.61674 2018 3.73321 2019 3.65793 2020 3.67728