Year	% (national estimate)
1961	11.16566648481542
1972	10.471607314725699
1976	8.124856552673858
1977	8.125789050843569
1978	8.073394495412845
1979	8.088572739788894
1980	8.073394495412845
1981	14.528236516918813
1982	14.533271719038817
1983	13.297309996475978
1984	13.2605120977214
1985	10.519062930638494
1986	11.24780316344464
1988	13.32312404287902
1989	44.337811900191944
1990	13.32312404287902
1991	16.712558362265057
1992	16.712558362265057
1993	17.406101859730157
1994	17.835088993824918
1995	15.39676752946895
1997	18.023115819889238
1998	18.51582393597672
2000	19.55031862450403
2002	19.63012208388734
2004	21.711798839458414
2005	20.506058073950282
2006	23.83033451121905
2007	24.360979393696745
2008	25.166288737717313
2009	26.64599025254763
2010	28.009746935045815
2011	28.466410602090914
2012	27.097958603214007
2013	28.87643852210781
2014	29.52095199349064
2015	30.380413651243586
2016	29.271140051625956
2018	27.206651067854832
2019	29.462228233643923
2021	30.409719209074566