Year	% (national estimate)
1971	31.15
1974	31.6
1978	34.24
1979	53.04
1981	53.68
1983	53.18
1985	51.62
1986	48.91
1987	45.82
1988	45.47
1989	44.65
1990	44.78
1992	48.3
1994	48.5
1997	51.3
2000	53.74
2007	59.94
2008	60.54
2009	59.37
2010	58.407
2011	57.878
2012	58.812
2013	59.107
2014	59.889
2015	58.521
2016	57.371
2019	54.91
2020	52.762
2021	51.867
2022	52.3