Year % 2001 15.12 2002 14.69 2003 14.67 2004 15.11 2005 15.36 2006 13.08 2007 13.82 2008 13.81 2009 13.82 2010 14.12 2011 14.21 2012 13.97 2013 14.13 2014 13.75 2015 12.84 2016 12.92 2017 18.36 2018 18.5 2019 16.05 2020 11.71 2021 11.74