Year Percent 2000 8.9964 2001 9.55376 2002 10.11111 2003 10.67798 2004 11.24585 2005 11.81471 2006 12.38456 2007 12.95541 2008 13.52725 2009 14.10009 2010 14.67392 2011 15.24874 2012 15.82456 2013 16.40137 2014 16.97918 2015 17.55798 2016 18.13777 2017 18.71856 2018 19.30035 2019 19.88313 2020 20.4669 2021 21.05166 2022 21.63742