Year % 1992 17.02 1995 13.94 1997 12.3 1998 12.33 1999 12.39 2000 12.34 2001 12.37 2002 12.72 2003 12.7 2004 12.38 2005 12.37 2006 13.09 2007 13.09 2008 13.21 2009 13.21 2010 13.21 2011 13.21 2012 13.21 2013 13.2 2014 12.9 2015 13.34 2016 13.07 2017 15.25 2018 15.25 2019 15.25 2020 15.25 2021 15.25