Year	% (national estimate)
1960	50.63
1970	42.86
1980	38.54
1981	37.77
1982	38.68
1983	37.38
1984	38.89
1985	40.74
1986	39.44
1988	39.27
1989	38.86
1990	39
1991	37.69
1992	38.62
1993	41.18
1994	41.68
1995	39.08
1996	43.596
1997	42.946
1998	41.353
1999	40.359
2000	38.557
2001	37.063
2002	36.311
2003	36.084
2004	36.351
2005	36.2
2006	36.618
2007	37.145
2008	39.537
2009	38.429
2010	37.574
2011	38.573
2012	37.336
2013	36.456
2014	36.702
2015	36.089
2016	35.104
2017	35.286
2018	34.559
2019	32.767
2020	26.582
2021	26.83
2022	29.675
2023	30.204