Year % 1982 11.6 1992 12.2 2000 12.2 2002 12.3 2006 12 2007 12 2008 12 2009 12.3 2010 12.5 2011 12.6 2012 12.7 2013 12.4 2014 12.5 2015 12.5 2016 12.4 2017 12.5 2018 12.4 2019 12.2 2020 12.2