Year % 1994 13.4 1999 17.42 2001 17.12 2002 17.08 2003 17.76 2004 17.82 2005 17.76 2006 17.76 2007 17.76 2008 14.09 2009 13.37 2010 12.07 2012 11.87 2013 11.94 2014 12.1 2015 12.02 2016 12.54 2017 12.52 2018 12.7 2019 12.7 2020 12.7 2021 12.65