Year % 1989 19.4 1992 19 1994 18.9 1996 19.5 1998 19.6 2000 19.1 2002 19.6 2004 19.6 2005 19.7 2006 19.5 2008 19.9 2010 20.4 2012 19.5 2014 19.3 2016 19.9 2018 20 2020 20.6 2022 20.7