Year	Percent
1960	49.97735
1961	43.4337
1962	56.73024
1963	56.99148
1964	46.66175
1965	37.02574
1966	30.34665
1967	34.2477
1968	30.24424
1969	24.92032
1970	26.57462
1971	25.70708
1972	23.09236
1973	34.52396
1974	39.93756
1975	39.7277
1976	43.83652
1977	21.41925
1978	20.87294
1979	20.84714
1980	27.76048
1981	15.21418
1982	14.68826
1983	12.29597
1984	10.97498
1985	11.70522
1986	13.50062
1987	10.45445
1988	16.80888
1989	15.71053
1990	11.99281
1991	13.25781
1992	8.60307
1993	7.70801
1994	11.70376
1995	4.452
1996	5.71341
1997	6.09812
1998	7.49482
1999	6.26035
2000	3.38714
2001	11.48723
2002	13.31963
2003	6.06173
2004	6.41531
2005	6.25183
2006	6.95929
2007	6.20579
2008	2.91315
2009	7.69174
2010	9.34205
2011	11.00924
2012	5.31755
2013	5.66271
2014	8.93729
2015	7.93645
2016	5.92468
2017	4.26755
2018	2.2818
2019	4.04046
2020	5.82186
2021	5.32673