Year % of total labor force 1991 16.7467938334478 1992 17.16102401601067 1993 17.56893559583494 1994 17.97397115722828 1995 18.376263667673516 1996 18.78088021775347 1997 19.187695676720672 1998 19.592041563348683 1999 19.9866688466037 2000 20.36494325650952 2001 20.73184137747486 2002 21.055378934070053 2003 21.264461207009525 2004 21.25671717631719 2005 21.174031892634197 2006 21.11836530881454 2007 21.084524020627235 2008 21.07849722004711 2009 21.114499659222727 2010 21.30348172527282 2011 20.918327876653244 2012 20.7547385737787 2013 20.914169966544634 2014 21.4654489827797 2015 21.546416433764787 2016 21.201707319202104 2017 20.911268404862167 2018 21.000489194154305 2019 21.23210335859918 2020 21.218230614054402 2021 21.397127441878318 2022 21.52568995785269 2023 21.780753208519574