Year	% (national estimate)
1961	57.16
1970	55.1
1981	22.19
1983	43.869
1984	42.24
1985	42.325
1986	42.715
1987	41.504
1988	37.675
1989	35.994
1990	35.543
1991	36.481
1992	36.214
1993	34.408
1994	35.193
1995	33.879
1996	32.766
1997	32.033
1998	32.634
1999	32.87
2000	35.731
2001	33.611
2002	33.834
2003	33.507
2004	34.027
2005	35.016
2006	34.695
2007	33.867
2008	33.403
2009	32.443
2010	32.51
2011	31.982
2012	31.479
2013	30.989
2014	30.195
2015	30.002
2016	28.458
2017	28.082
2018	29.632
2019	30.983
2020	28.431
2021	30.258
2022	31.063
2023	31.573