Year	Percent
1960	17.14506
1961	23.08252
1962	27.51408
1963	25.97316
1964	30.43609
1965	20.63876
1966	22.57398
1967	22.25313
1968	21.51855
1969	23.65119
1970	16.739
1971	19.91274
1972	20.54771
1973	26.87683
1974	39.98777
1975	26.88163
1976	23.84391
1977	59.2151
1978	56.1056
1979	75.52792
1980	88.48722
1981	68.37188
1982	68.05014
1983	72.68449
1984	61.07956
1985	19.30689
1986	29.39482
1987	31.21484
1988	22.18482
1989	44.89687
1990	37.7414
2013	54.89389
2014	59.43644
2015	60.89044
2016	62.24013
2017	64.20521