Year	Percent of total labor force
1990	16.198
1991	16.223
1992	16.247
1993	16.272
1994	16.296
1995	16.177
1996	16.058
1997	15.939
1998	16.063
1999	15.982
2000	15.691
2001	15.126
2002	15.263
2003	14.514
2004	14.237
2005	12.819
2006	12.511
2007	12.397
2008	12.442
2009	13.29
2010	13.048
2011	18.889
2012	16.723
2013	15.33
2014	14.959
2015	15.39
2016	15.544
2017	15.513
2018	15.612