Year % of total labor force 1991 0.5809380447138556 1992 0.5547211061842406 1993 0.5110527599437923 1994 0.49955077064365255 1995 0.500670614226281 1996 0.5222917113090816 1997 0.4684045355475875 1998 0.44382301467559965 1999 0.4360506070547565 2000 0.42002536217376674 2001 0.3985375540851938 2002 0.3609047577617226 2003 0.3527522492107598 2004 0.40174915925500765 2005 0.3984624288933975 2006 0.35485554385271545 2007 0.3481568359506749 2008 0.34293045648973386 2009 0.3498076249673928 2010 0.3460445267132681 2011 0.3431392288204362 2012 0.3416891163318907 2013 0.33655716162135724 2014 0.3584395014627344 2015 0.3427960968576212 2016 0.33956585072262635 2017 0.35741061371522526 2018 0.35580465813167955 2019 0.3466877619749685 2020 0.35151730736961406