Year % of total labor force 1991 35.28151073004125 1992 35.70273346512115 1993 36.135336743884 1994 36.57964235384682 1995 37.11125627901066 1996 37.27676977865364 1997 37.716681000559085 1998 37.999185178333484 1999 38.214180547901684 2000 38.41035064641078 2001 38.79309661014994 2002 39.09305043427481 2003 39.36612510417889 2004 39.773677849323576 2005 40.11522588879925 2006 40.276599096688166 2007 40.40199550959912 2008 40.4433432132311 2009 40.786337769499994 2010 40.6996735223919 2011 40.60030639136926 2012 40.7806777754314 2013 40.80407311346469 2014 40.75989885676874 2015 40.92922531509048 2016 41.11292085702273 2017 41.254678947648394 2018 41.47826696788385 2019 41.748038209677816 2020 41.14049076044388 2021 41.52348190957639 2022 41.72811340897086 2023 41.86555233512079