Year	% (national estimate)
1977	47.92
1978	46.48
1979	45.16
1980	43.21
1981	41.42
1982	40.45
1983	39.67
1984	38.09
1986	37.023
1987	38.072
1988	38.723
1989	39.878
1990	40.663
1991	40.528
1992	40.998
1993	38.808
1994	38.071
1995	38.698
1996	39.205
1997	40.294
1998	41.56
1999	43.627
2000	45.496
2001	46.702
2002	47.779
2003	48.737
2004	49.657
2005	51.869
2006	53.08
2007	53.755
2008	52.69
2009	48.879
2010	47.785
2011	46.911
2012	44.925
2013	43.883
2014	44.55
2015	45.853
2016	47.032
2017	48.107
2018	49.088
2019	49.751
2020	47.91
2021	49.232
2022	50.411
2023	50.992