Year	Percent of total labor force
1980	0.607
1981	0.232
1982	0.154
1983	0.173
1984	0.117
1985	0.041
1986	0.212
1987	0.315
1988	0.463
1989	0.531
1990	2.082
1991	8.415
1992	9.303
1993	11.29
1994	10.118
1995	10.17
1996	9.886
1997	8.731
1998	7.8
1999	6.95
2000	6.4
2001	5.725
2002	5.8
2003	5.85
2004	6.075
2005	7.2
2006	7.475
2007	7.4
2008	7.816
2009	10.031
2010	11.171
2011	11.028
2012	11.003
2013	10.178
2014	7.726
2015	6.814
2016	5.115
2017	4.156
2018	3.708
2019	3.529
2020	3.35
2021	3.362
2022	3.374
2023	3.387
2024	3.399