Year % 1993 29.28 1997 15.97 2001 18.67 2002 18.09 2003 16.27 2004 19.85 2005 16.4 2006 19.75 2007 18.24 2008 18.22 2009 16.55 2010 16.54 2011 16.52 2012 17.31 2013 17.24 2015 17 2016 18.24 2018 17.66 2020 17.67 2021 19.72