Year % 2000 4.890049379550076 2001 4.721109508685006 2002 4.602780524263204 2003 4.430973948159185 2004 4.286658891704845 2005 4.17343531645627 2006 4.084581301981822 2007 4.033455689866572 2008 4.003935151411536 2009 3.918101135925004 2010 3.8440249461094553 2011 3.670177913059378 2012 3.5699025742269708 2013 3.506703997856874 2014 3.440918180200502 2015 3.3156295102657816 2016 3.232219493770605 2017 3.1213439382127626 2018 3.0381923973012643 2019 2.937117778559455 2020 2.80563123685699