Year	Percent
1965	37.73621
1966	35.12952
1967	33.7855
1968	24.81531
1969	28.36047
1970	45.14627
1971	33.35552
1972	38.51498
1973	36.24589
1974	26.8711
1975	17.47705
1976	19.56503
1977	32.10094
1978	23.9633
1979	43.35572
1980	42.37096
1981	40.91181
1982	43.14464
1983	36.3849
1984	32.67128
1985	31.87403
1986	45.05035
1987	51.47252
1988	47.16919
1989	54.76102
1990	54.32188
1991	47.09311
1992	55.17251
1993	36.23998
1994	42.16432
1995	34.32017
1996	26.93602
1997	25.29942
1998	25.51102
1999	28.34249
2000	23.2978
2001	25.91496
2002	27.30449
2003	33.41511
2004	24.07894
2005	18.93611
2006	18.63401
2007	18.8043
2008	16.16152
2009	17.41247
2010	12.52937
2011	12.48916
2012	12.39885
2013	13.27856
2014	12.54778
2015	16.06996
2016	15.36995
2017	11.74117
2018	11.09113
2019	9.42102
2020	17.28209
2021	12.07192