Year % 1997 14.58 2000 10.41 2001 10.41 2002 7.6 2003 7.27 2004 6.05 2005 5.54 2006 5.49 2007 5.39 2008 5.41 2009 5.07 2010 5.07 2011 5.07 2012 4.74 2013 4.74 2014 4.71 2015 4.68 2016 4.68 2017 4.73 2018 4.73 2019 4.73 2020 4.73 2021 4.74