Year Percent 2000 3.92433 2001 3.71753 2002 3.68557 2003 3.74109 2004 3.75637 2005 3.70239 2006 4.13203 2007 3.61241 2008 3.96381 2009 3.90816 2010 3.81482 2011 3.7586 2012 3.65945 2013 3.73684 2014 3.34204 2015 2.91802 2016 3.11767 2017 3.53641 2018 3.45077 2019 3.39222 2020 3.32369 2021 3.45771