Year % 1999 38.11 2000 38.11 2001 38.11 2002 38.36 2003 38.36 2004 38.36 2005 38.37 2006 38.36 2007 38.54 2008 38.51 2009 38.51 2010 38.51 2011 38.51 2012 38.51 2013 38.29 2014 38.29 2015 38.29 2016 38.29 2017 38.3 2018 38.3 2019 38.3 2020 38.3 2021 38.3