Year	Percent
1960	32.18654
1961	35.21184
1962	35.88547
1963	44.08357
1964	30.18043
1965	26.30631
1966	25.16557
1967	24.10181
1968	18.38134
1969	18.62155
1970	18.54749
1971	13.79638
1972	13.08756
1973	11.6077
1974	8.20554
1975	6.40139
1976	5.00626
1977	5.46218
1978	6.50964
1979	7.44648
1980	6.75736
1981	6.1172
1982	6.12331
1983	6.50004
1984	6.10461
1985	6.75108
1986	9.24493
1987	10.9926
1988	10.07618
1989	8.68589
1990	7.32445
1991	7.62367
1992	8.25139
1993	8.48423
1994	9.08602
1995	8.03167
1996	7.09283
1997	7.21752
1998	7.02079
1999	7.29363
2000	6.21362
2001	6.14393
2002	5.74386
2003	6.00402
2004	5.46729
2005	4.98464
2006	4.9112
2007	4.95783
2008	4.22984
2009	5.04417
2010	3.91445
2011	3.43229
2012	3.3537
2013	3.32908
2014	3.6212
2015	4.31163
2016	4.97314
2017	5.26576
2018	5.43595
2019	5.55443
2020	6.62815
2021	6.01649
2022	5.64221