Year	% (national estimate)
1974	29.8
1976	30.45
1978	33.06
1979	33.58
1980	33.56
1981	33.84
1982	33.94
1983	34.65
1984	34.92
1985	34.43
1986	35.46
1987	36.05
1988	37
1989	37.06
1990	40.174
1991	39.563
1992	40.392
1993	42.211
1994	44.709
1995	46.312
1996	46.624
1997	46.087
1998	45.868
1999	46.766
2000	47.764
2001	47.68
2002	46.874
2003	47.153
2004	47.57
2005	49.222
2006	49.744
2007	50.871
2008	51.888
2009	52.127
2010	52.946
2011	53.179
2012	55.293
2013	55.573
2014	56.689
2015	56.958
2016	57.508
2017	57.759
2018	58.532
2019	58.321
2020	57.074
2021	56.902
2022	58.957