Year % 1993 21.55 1997 24.9 1998 24.23 2001 22.19 2002 18.93 2003 18.34 2005 16.37 2006 16.05 2007 16.21 2008 16.07 2009 14.2 2014 11.82 2015 11.9 2016 12 2017 12.11 2018 12.27 2019 12.27 2020 12.31 2021 12.63