Year	% of total labor force (national estimate)
1991	2.5742041864253338
1992	2.548507095689844
1993	2.794312145600729
1994	3.117664604315596
1995	3.0573555064218816
1996	3.225263351117744
1997	3.320588691565724
1998	3.5442526826966176
1999	3.5969113509844437
2000	4.069035355309498
2001	3.7834925116781517
2002	4.205109659443135
2003	4.308367638186875
2004	4.3308518888696765
2005	4.466975599836674
2006	4.370206281596101
2007	4.2013085074871155
2008	4.3774878307187
2009	4.225339892218144
2010	3.9376540397393156
2011	3.87796338485753
2012	3.802499173429912
2013	3.7440379749318526
2014	3.758874755949374
2017	3.531863472845632
2018	4.298313333933301
2019	4.33959802752366
2020	4.8267666636952615
2021	4.551939945434292