Year Percent 2000 16.37949 2001 16.5976 2002 16.81515 2003 17.03215 2004 17.2487 2005 17.46425 2006 17.67944 2007 17.89386 2008 18.10774 2009 18.32081 2010 18.53329 2011 18.74505 2012 18.95618 2013 19.16629 2014 19.37585 2015 19.58459 2016 19.79224 2017 19.99878 2018 20.20395 2019 20.40809 2020 20.61083 2021 20.81214 2022 21.01213