Year % 1993 18.92 1997 19.51 1998 18.68 2001 17.29 2002 13.05 2003 12.49 2005 11.97 2006 12.2 2007 11.79 2008 12.11 2009 12.18 2014 12.73 2015 12.09 2016 12.67 2017 13.16 2018 14.19 2019 14.2 2020 14.42 2021 14.42