Year Percent 1990 3.89079 1991 3.93655 1992 3.42093 1993 3.48975 1994 3.83872 1995 3.21856 1996 3.24733 1997 3.77043 1998 3.67264 1999 3.69083 2000 3.7525 2001 2.96039 2002 2.91348 2003 2.92842 2004 2.7731 2005 2.71531 2006 2.69582 2007 2.65875 2008 2.57884 2009 2.48156 2010 2.37566 2011 2.27123 2012 2.22551 2013 2.14439 2014 2.09535 2015 1.69446 2016 1.64238 2017 1.59168 2018 1.55806 2019 1.53989 2020 1.63258