Year % 1996 18.71 1997 14 1998 14.03 1999 16.45 2000 15 2001 11.22 2002 12.5 2003 12.03 2006 11.9 2007 11.73 2010 11.41 2011 13.26 2012 11.93 2013 13.26 2015 11.98 2016 11.98 2017 11.98 2020 12.35