Year Percent 2000 30.00435 2001 30.24237 2002 30.66965 2003 31.09989 2004 31.53309 2005 31.96924 2006 32.40835 2007 32.85042 2008 33.29544 2009 33.74342 2010 34.19435 2011 34.64824 2012 35.10508 2013 35.56488 2014 36.02764 2015 36.49335 2016 36.96202 2017 37.43365 2018 37.90823 2019 38.38576 2020 38.86626 2021 39.34971 2022 39.83611