Year	% (national estimate)
1960	66.13
1970	56.33
1978	57.82
1988	49.14
1992	49.18
1993	46.183
1994	45.22
1995	43.87
1996	43.417
1997	40.122
1998	38.643
1999	37.679
2000	40.188
2001	42.855
2002	41.431
2003	40.356
2004	38.987
2005	39.474
2006	37.539
2007	36.542
2008	36.522
2009	38.058
2010	39.286
2011	38.702
2012	38.529
2013	38.386
2014	38.765
2015	38.389
2016	39.79
2017	39.686
2018	39.217
2019	39.177
2020	36.064
2021	35.707
2022	35.647
2023	36.127