Year Percent 2000 15.91107 2001 16.17488 2002 16.4387 2003 16.70252 2004 17.4927 2005 18.29926 2006 19.12218 2007 19.96147 2008 20.81714 2009 21.68917 2010 22.57757 2011 23.48234 2012 24.40348 2013 25.34099 2014 26.29487 2015 27.26512 2016 28.25174 2017 29.25473 2018 30.27409 2019 31.30981 2020 32.36191 2021 33.43038 2022 34.51521