Year	Percent
1960	22.62825
1961	35.39344
1962	43.20687
1963	26.34376
1964	11.68834
1965	10.10794
1966	9.9698
1967	15.56592
1968	19.96682
1969	16.30113
1970	15.98512
1971	16.58181
1972	22.06338
1973	6.26881
1974	11.67741
1975	25.02899
1976	30.77301
1977	28.3802
1978	22.49343
1979	18.52323
1980	26.29568
1981	30.40645
1982	34.21271
1983	26.3947
1984	24.44639
1985	28.17294
1986	29.77979
1987	28.32064
1988	27.99189
1989	18.58508
1990	19.96618
1991	20.94303
1992	20.67183
1993	14.32651
1994	49.099
1995	20.37733
1996	17.625
1997	15.13975
1998	13.97155
1999	17.77247
2000	20.63031
2001	23.53525
2002	14.58796
2003	26.22271
2004	47.23851
2005	61.46868
2006	30.82175
2007	31.75215
2008	41.67905
2009	34.85517
2010	39.19273
2011	43.42877
2012	58.82612
2013	56.02061
2014	52.19634
2015	54.76766
2016	47.66877
2017	56.83316