Year	% (national estimate)
1961	79.22
1971	66.33
1977	48.73
1978	47.92
1979	48.68
1980	49.36
1981	61.26
1982	50.01
1983	53.709
1984	54.23
1985	53.244
1986	52.809
1987	52.785
1988	53.295
1989	52.363
1990	50.685
1991	50.608
1992	46.548
1993	46.066
1994	43.959
1995	43.893
1996	43.327
1997	42.749
1998	43.738
1999	42.429
2000	42.179
2001	40.105
2002	39.602
2003	39.082
2004	41.429
2005	38.82
2006	37.606
2007	35.989
2008	35.742
2009	33.791
2010	32.819
2011	31.221
2012	32.888
2013	30.687
2014	30.992
2015	30.447
2016	30.23
2017	29.972
2018	29.946
2019	29.829
2020	28.484
2021	29.395
2022	30.121
2023	30.824