Year % (national estimate) 1960 23.788950838419346 1970 26.322837001435627 1980 32.518127363735005 1990 37.10628357195424 1991 39.707337857982516 1992 43.381079608663484 1993 41.702006825131015 1995 42.90854251711033 1996 42.65195769340732 1997 44.180183259425434 1998 44.16524656348207 1999 44.70478684202738 2001 44.66748963372419 2002 46.114026414846364 2003 45.20360911526648 2004 45.467024149173234 2005 45.05613577797836 2006 44.880969692321834 2007 44.50956145045288 2008 43.89093570684061 2009 43.82585720052194 2011 41.59949271649125 2012 40.91245960026092 2013 40.66038574165457 2014 39.87661887962289 2015 40.29828729860309 2016 39.86377220182168 2017 40.060331152035744 2018 40.87245739417913 2019 41.560279943096035 2020 37.11019712596698 2021 41.09385635334862 2022 41.434418784559334 2023 40.872372255267685