Year	Percent
1960	0.02855
1961	0.19375
1962	5.07902
1963	14.42513
1964	47.08948
1965	35.63501
1966	37.72064
1967	25.13489
1968	28.7525
1969	24.25829
1970	23.11873
1971	20.03334
1972	19.34165
1973	15.37127
1974	18.42804
1975	18.64156
1976	31.05074
1977	23.64913
1978	33.41539
1979	28.96811
1980	14.94037
1981	8.37795
1982	7.12381
1983	13.31622
1984	14.47822
1985	10.54698
1986	19.68892
1987	30.33912
1988	21.02172
1989	26.8121
1990	48.78302
1991	23.82534
1992	18.1512
1993	15.70656
1994	37.74147
1995	16.39275
1996	51.76897
1997	52.02558
1998	12.49311
1999	21.49034
2000	4.402
2001	10.02418
2002	8.0437
2003	7.57877
2004	11.04249
2005	82.64646
2006	11.31343
2007	2.16927
2008	9.92867
2009	5.37896
2010	21.19489
2011	4.52933
2012	1.80755
2013	1.7864
2014	1.1213
2015	0.93006
2016	1.11741
2017	1.97078
2018	3.35995
2019	4.88043
2020	7.90908
2021	5.95016