Year % 1996 18.84 1999 16.57 2001 11.18 2002 10.95 2003 10.79 2006 11.46 2007 10.97 2008 10.56 2009 13.06 2010 13.06 2011 10.21 2012 9.65 2013 11.51 2014 11.51 2015 11.48 2016 11.47 2017 11.47 2018 11.49 2019 11.52 2020 10.4 2021 10.37