Year % of total labor force 1991 33.0082119661032 1992 32.93879534941348 1993 32.82666438611142 1994 32.65116063605555 1995 32.38412111935519 1996 32.06128921824537 1997 31.743268155104225 1998 31.428873346228876 1999 31.15522248934226 2000 30.947989648385267 2001 30.67160896772843 2002 30.506098063476905 2003 30.420033212637055 2004 30.369950049514 2005 30.33951101426173 2006 30.213499840255096 2007 30.102231582337563 2008 30.02292856179472 2009 30.00500807862112 2010 30.07058262333862 2011 30.086973099866498 2012 30.191126389916466 2013 30.35383681532548 2014 30.530480858125124 2015 30.693207183462157 2016 30.844964285490704 2017 30.973687765599355 2018 31.093325805400518 2019 31.2250377145672 2020 31.22045926998924 2021 31.37056716347173 2022 31.205719049451137 2023 31.25219727635389