Year	% (national estimate)
1981	28.43
1982	27.33
1983	29.681
1984	29.857
1985	30.645
1986	30.594
1987	30.241
1988	30.733
1989	31.128
1990	31.092
1991	28.722
1992	29.616
1993	29.404
1994	29.972
1995	30.339
1996	30.905
1997	30.633
1998	32.297
1999	32.52
2000	32.926
2001	32.657
2002	33.187
2003	33.913
2004	34.446
2005	34.97
2006	36.077
2007	36.334
2008	37.056
2009	37.185
2010	36.358
2011	33.9
2012	31.111
2013	29.633
2014	30.411
2015	31.461
2016	31.968
2017	32.702
2018	33.226
2019	34.557
2020	35.007
2021	35.314
2022	37.349
2023	38.445