Year	Percent
1960	0.00171
1961	35.54648
1962	33.58436
1963	33.01745
1964	43.25018
1965	38.453
1966	38.49766
1967	33.26545
1968	35.44747
1969	37.71104
1970	46.93491
1971	41.87085
1972	40.2199
1973	39.81744
1974	54.98166
1975	48.70281
1976	46.88467
1977	57.06934
1978	82.96276
1979	82.66034
1980	78.22889
1981	66.7119
1982	69.49415
1983	58.11322
1984	64.4713
1985	62.70006
1986	48.63741
1987	53.47854
1988	52.87024
1989	52.99532
1990	52.13619
1991	43.43756
1992	39.51661
1993	25.53715
1994	55.97256
1995	74.23344
1996	75.40355
1997	71.31655
1998	63.50223
1999	62.68659
2000	71.46995
2001	68.30145
2002	69.03426
2003	82.03429
2004	76.4555
2005	81.33445
2006	77.85493
2007	75.84856
2008	74.66581
2009	76.24254
2010	83.79961
2011	89.61601
2012	95.54142
2013	105.15627
2014	85.99968
2015	81.86656
2016	75.10979
2017	76.15016