Year % 1996 21.98 1999 18.98 2000 14.34 2001 14.46 2002 14.54 2003 14.9 2006 12.88 2007 12.33 2008 12.24 2009 14.02 2010 12.16 2011 11.84 2012 11.64 2013 11.64 2014 11.65 2015 11.66 2016 11.68 2017 13.54 2018 13.59 2019 14.3 2020 10.03