Year Percent 1990 3.16526 1991 3.42477 1992 2.33379 1993 2.27119 1994 1.89417 1995 2.9175 1996 2.83621 1997 2.75672 1998 2.67898 1999 2.60284 2000 1.78283 2001 1.73077 2002 1.67924 2003 1.62815 2004 1.41254 2005 1.59487 2007 1.49208 2008 1.44095 2009 1.33101 2010 1.28353 2011 1.23794 2012 1.1937 2013 1.15136 2014 1.11252 2015 1.0783 2016 1.04607 2017 1.0636 2018 0.99247 2019 1.01181 2020 1.03775