Year Percent 2000 20.59194 2001 20.60757 2002 20.6232 2003 20.63883 2004 20.65446 2005 21.85176 2006 23.04947 2007 24.3296 2008 25.61761 2009 26.92019 2010 28.23805 2011 29.57155 2012 30.92076 2013 32.28639 2014 33.66852 2015 35.06824 2016 36.48563 2017 36.57503 2018 36.6727 2019 36.77826 2020 36.89208