Year Percent 2000 50.02019 2001 50.72769 2002 51.43399 2003 52.13943 2004 52.84365 2005 53.54664 2006 54.24873 2007 54.94956 2008 55.64913 2009 56.34743 2010 57.04478 2011 58.18184 2012 59.32821 2013 60.48388 2014 61.64879 2015 62.82726 2016 64.01924 2017 65.22465 2018 66.44346 2019 67.67525 2020 68.92063 2021 70.1792 2022 71.45121