Year % 1992 20.7 1993 26.6 1996 25.8 2002 26.6 2004 27.5 2005 26.9 2006 26.7 2007 26 2008 26.3 2009 26.2 2010 26.6 2011 26.4 2012 26.1 2013 26.5 2014 25.9 2015 25.9 2016 25.4 2017 24.9 2018 25 2019 25.3 2020 26.2 2021 26.2