Year % 2000 7.44222356024858 2001 6.50146424949607 2002 6.15022658283611 2003 5.95309744257472 2004 5.47101466482882 2005 5.29284160971464 2006 4.7663072732025 2007 4.6136753799637 2008 4.6057282480751 2009 4.15903110273031 2010 4.12764748502915 2011 3.99527913581932 2012 3.96134020638693 2013 3.64067256385418 2014 3.6009449296073 2015 3.51051745416855 2016 3.10392846183506 2017 3.2550969242469 2018 2.78532945200309 2019 3.05093223241537 2020 3.12417568630982