Year	Percent
1960	11.46063
1961	12.76159
1962	12.34542
1963	13.01928
1964	11.98094
1965	14.31398
1966	13.44633
1967	12.84461
1968	11.38689
1969	9.6657
1970	10.65195
1971	13.0409
1972	12.87477
1973	11.30911
1974	10.64545
1975	13.111
1976	14.19878
1977	16.39146
1978	16.12832
1979	14.93009
1980	13.98355
1981	15.62518
1982	13.46202
1983	14.19927
1984	14.54472
1985	13.08276
1986	12.17138
1987	10.88388
1988	16.40171
1989	19.14076
1990	18.20258
1991	15.81403
1992	21.26755
1993	30.47873
1994	11.8265
1995	14.08937
1996	13.29824
1997	13.98255
1998	15.86841
1999	18.18997
2000	16.14977
2001	15.52748
2002	15.36143
2003	15.6171
2004	15.58094
2005	14.58855
2006	13.20627
2007	12.1056
2008	11.454
2009	11.55278
2010	9.42095
2011	9.64806
2012	9.32164
2013	8.22652
2014	6.7796
2015	4.98084
2016	6.22847
2017	4.02427
2018	3.34112
2019	2.86077
2020	2.97709
2021	3.00092
2022	3.09402