Year % 1980 47.4 1988 41.2 1989 42.3 1991 39.5 1992 40.5 1996 45.6 1999 46.9 2000 47 2001 46.3 2002 45.2 2003 42.8 2004 44.5 2005 43.2 2008 43.7 2009 42.9 2010 43.4 2011 42.4 2012 41.3 2013 41.4 2014 41.4 2015 39.9 2016 39.8 2017 39 2018 39.7 2019 40.3 2020 41.8 2021 43.7 2022 43.5