Year % 2000 18.47 2001 18.77 2002 17.99 2003 17.82 2004 17.37 2005 18.08 2006 17.98 2008 17.53 2009 17.65 2010 17.88 2011 17.93 2012 7.7 2013 7.58 2014 6.91 2015 6.62 2016 6.6 2017 7.05 2018 7.48 2019 14.17 2020 7.6 2021 8.97