Year % 1992 14.23 1993 12.89 1995 13.13 1996 13.91 1997 14.07 1998 16.39 1999 16.18 2000 16.1 2001 13.26 2002 14.95 2003 15.81 2004 13.1 2005 12.01 2006 11.98 2007 13.14 2008 12.96 2009 14.15 2010 14.04 2011 13.79 2012 13.74 2013 15.02 2014 15.31 2015 15.31 2016 15.31 2017 15.39 2018 14.92 2019 14.72 2020 14.64 2021 14.61