Year	Percent
1960	10.98848
1961	8.15918
1962	8.87127
1963	10.6267
1964	11.02407
1965	10.7509
1966	14.84206
1967	15.1493
1968	9.81478
1969	8.78017
1970	7.2542
1971	7.75017
1972	4.39444
1973	4.86937
1974	5.49168
1975	8.34012
1976	8.74626
1977	3.85827
1978	3.6372
1979	3.77626
1980	5.99946
1981	3.98828
1982	3.24243
1983	3.98618
1984	3.37136
1985	2.58092
1986	3.06617
1987	2.35266
1988	2.49854
1989	2.22096
1990	1.58986
1991	4.02546
1992	3.0665
1993	2.31109
1994	2.69702
1995	1.64983
1996	2.12944
1997	1.54074
1998	1.52893
1999	1.04952
2000	1.15025
2001	1.19131
2002	1.11584
2003	0.38466
2004	0.31272
2005	0.61095
2006	0.37732
2007	0.26041
2008	0.43669
2009	0.46634
2010	0.42471
2011	0.45309
2012	0.23997
2013	0.38884
2014	0.42816
2015	0.46985
2016	0.38692
2017	0.38931
2018	0.28162
2019	0.29884
2020	0.23358
2021	0.31704