Year % 2000 4.26739225977071 2001 4.22288063051334 2002 4.23108892573516 2003 4.1819210070692 2004 4.11304654909595 2005 4.06397406819179 2006 3.96989554178102 2007 4.03312749392072 2008 3.98908675680437 2009 3.88734745898666 2010 3.88415747056839 2011 3.7883206942423 2012 3.85302079645403 2013 3.79430374673224 2014 3.73104064937913 2015 3.76117253718418 2016 3.66826136039322 2017 3.72307817362059 2018 3.38073412792908 2019 3.37057415801372 2020 3.41527189289153