Year % of total labor force 1991 35.15598565338025 1992 35.46247198988308 1993 35.94206691968765 1994 35.944143483046645 1995 36.49076573225937 1996 36.677247787424584 1997 37.00825037926806 1998 37.36331497163528 1999 37.62753283779656 2000 37.800367817950324 2001 38.01561653184528 2002 38.47744809482141 2003 38.99213653652864 2004 39.29858934169279 2005 39.53311490755909 2006 39.976394559139365 2007 40.18691588785047 2008 40.301332670503434 2009 40.21080318682576 2010 40.03846007387381 2011 40.022815857020625 2012 40.1112777957122 2013 40.23348519362187 2014 40.309724436347075 2015 40.372399931739324 2016 40.523990976132254 2017 40.645430255253835 2018 40.82778702163062 2019 40.90307453768483 2020 40.8808847998434 2021 41.274291791549835 2022 41.175356885910105 2023 41.41349415755749