Year	% (national estimate)
1960	21.319961177612424
1970	22.245657568238215
1975	28.038255190109634
1978	30.90371513047949
1979	32.23225806451613
1980	36.36583303129154
1988	43.01675977653631
1990	28.548728813559322
1991	41.32964373791522
1992	42.2310250843073
1993	44.68300657356988
1994	44.111314333341056
1995	46.34684700550644
1996	46.36986702595044
1997	48.35303662494205
1998	48.096350806217224
1999	47.558204899985945
2000	48.386144692104274
2001	47.95181295442666
2002	47.654570900184936
2003	48.471588422829285
2004	49.89627593101725
2005	50.935149673756044
2006	52.155492790248246
2007	52.84083126844392
2008	52.87656838339234
2009	54.1263733481849
2010	54.02297390022619
2011	54.68682285160732
2012	55.744448535479854
2013	55.994902835297864
2014	55.10196258816315
2015	55.68049233925251
2016	55.93933312750848
2017	55.47095427665906
2018	56.239587772655064
2019	57.96035681456259
2020	57.18194636400441
2021	57.641731139922356
2022	58.99965930235606
2023	60.56605503385592