Year % 1993 18.83 1997 19.51 1998 18.68 2001 17.29 2002 13.05 2003 12.49 2005 10.55 2006 10.1 2007 9.95 2008 9.6 2009 9.48 2014 7.66 2015 7.66 2016 8.36 2017 9.25 2018 10.03 2019 10.04 2020 10.26 2021 10.42