Year % 2000 11.5 2001 10.8 2002 10.3 2003 10.1 2004 9.3 2005 9.6 2006 9.1 2007 9 2008 8.8 2009 8.2 2010 8.2 2011 7.8 2012 7.8 2013 7.8 2014 7.5 2015 7.4 2016 7.2 2017 7 2018 6.8 2019 6.8