Year % (national estimate) 1960 81.4227722335263 1970 69.5336074136505 1980 70.00187801022936 1990 69.23552429679835 1991 71.10630786329325 1992 72.55066845403022 1993 72.50658198956029 1995 70.92165273751819 1996 70.00108296344204 1997 70.71090668226266 1998 70.54361498531797 1999 70.34047130648362 2001 68.680250372642 2002 68.8218181147249 2003 67.89823541731164 2004 67.05061980246346 2005 65.67454745019226 2006 66.78011469570605 2007 65.19246147205835 2008 64.07500035846819 2009 64.08190749410015 2011 62.02988344831232 2012 61.51587042813549 2013 60.60591090017953 2014 60.14406267911653 2015 60.376342040119944 2016 58.86052835583077 2017 58.624194924331086 2018 58.84915190030267 2019 58.95006320673838 2020 53.25278234661883 2021 57.54203644655235 2022 57.81318767905311 2023 55.87001487958389