Year Percent 2000 51.89988 2001 53.60843 2002 55.31485 2003 57.01914 2004 58.53309 2005 59.80226 2006 61.04359 2007 62.25746 2008 63.4541 2009 64.67667 2010 65.87016 2011 67.03474 2012 68.17061 2013 69.2777 2014 70.35671 2015 71.4076 2016 72.43058 2017 73.42565 2018 74.39437 2019 75.33672 2020 76.25311 2021 77.06604 2022 78.0065