Year	Percent
1960	15.46977
1961	16.11458
1962	9.94024
1963	7.94449
1964	7.3033
1965	7.84424
1966	6.91845
1967	8.04359
1968	6.81427
1969	6.91364
1970	5.94185
1971	4.18214
1972	7.44898
1973	5.22469
1974	3.77041
1975	5.1244
1976	5.35745
1977	3.84629
1978	2.44438
1979	3.19808
1980	3.3568
1981	2.63097
1982	3.55312
1983	5.68862
1984	4.43289
1985	6.80123
1986	16.37047
1987	24.18821
1988	19.65116
1989	20.98144
1990	17.86519
1991	14.218
1992	10.36896
1993	11.13129
1994	9.62848
1995	9.30707
1996	9.19426
1997	10.5279
1998	6.82554
1999	8.83618
2000	7.57793
2001	6.17817
2002	5.93017
2003	5.82802
2004	4.674
2005	5.0179
2006	7.95298
2007	6.54403
2008	8.40451
2009	7.72651
2010	6.97838
2011	4.87184
2012	4.04612
2013	5.9147
2014	3.20955
2015	4.46034
2016	2.8991
2017	3.76725
2018	3.94985
2019	3.51082
2020	4.5041
2021	3.52321