Year	Percent
1960	42.72364
1961	41.88696
1962	40.49861
1963	44.52349
1964	47.73968
1965	52.94005
1966	52.7742
1967	55.45763
1968	53.74836
1969	58.10583
1970	62.95362
1971	66.3357
1972	64.45211
1973	67.01089
1974	79.88593
1975	76.11431
1976	69.6576
1977	80.78582
1978	76.21099
1979	81.38717
1980	86.68557
1981	84.02492
1982	81.94766
1983	75.43437
1984	78.4321
1985	79.22841
1986	79.79506
1987	73.98576
1988	76.36804
1989	82.73038
1990	73.60865
1991	81.16488
1992	77.93541
1993	78.07564
1994	75.49092
1995	88.56556
1996	82.8244
1997	78.47498
1998	79.48429
1999	88.09166
2000	92.209
2001	93.34558
2002	92.6151
2003	101.05186
2004	107.7591
2005	102.80271
2006	77.36063
2007	79.89841
2008	79.02886
2009	65.44337
2010	68.00813
2011	64.87885
2012	54.74142
2013	56.58637
2014	57.50425
2015	54.91075
2016	52.97638
2017	61.97615