Year	% (national estimate)
1960	58.42
1970	55.1
1977	52.6
1978	52.04
1979	51.47
1980	51.36
1983	57.45
1985	54.22
1987	53.93
1989	53.84
1990	54.2
1991	48.08
1992	52.7
1993	53.1
1994	54.1
1995	52.26
1996	55.7
1997	53.1
1998	50
1999	49.4
2004	47.274
2005	45.26
2006	45.504
2007	44.6
2008	42.552
2009	42.386
2010	41.054
2011	40.917
2012	40.522
2013	40.101
2014	38.603
2017	38.956
2018	39.406
2019	39.004
2020	33.099
2021	37.006
2022	38.024
2023	39.124