Year % 2003 13.76 2004 14.96 2006 17.13 2007 17.89 2008 19.12 2009 18.5 2010 18.26 2011 23.04 2012 17.96 2013 18.94 2015 10.87 2017 21 2018 23.01 2019 32.41 2020 22.39 2021 19.26