Year	Percent
1960	69.03693
1961	75.14137
1962	74.19144
1963	72.58163
1964	73.74609
1965	75.10344
1966	70.62349
1967	66.35302
1968	66.21327
1969	65.55173
1970	68.60544
1971	76.45577
1972	69.52672
1973	69.38702
1974	73.75853
1975	79.826
1976	74.52406
1977	74.95804
1978	74.59137
1979	78.66776
1980	80.81796
1981	81.08864
1982	82.10174
1983	81.56602
1984	90.02326
1985	93.67253
1986	85.23381
1987	86.86485
1988	86.79182
1989	86.12993
1990	85.06819
1991	85.99519
1992	81.06128
1993	79.69898
1994	80.76962
1995	82.13983
1996	83.9079
1997	94.73526
1998	106.71155
1999	108.38731
2000	123.46606
2001	123.90499
2002	116.87854
2003	115.20082
2004	128.17266
2005	136.09657
2006	144.35137
2007	149.61685
2008	156.44995
2009	131.9033
2010	141.63831
2011	145.45995
2012	155.41771
2013	158.61336
2014	174.06108
2015	187.46843
2016	186.16333
2017	193.96982