Year % 1996 18.71 1997 14 1998 14.03 1999 16.45 2000 15 2001 11.22 2002 12.5 2003 12.03 2006 9.12 2007 9.34 2010 11.41 2011 9.95 2012 9.88 2013 10.16 2015 11.82 2016 9.36 2017 9.28 2020 9.97