Year	Percent
1960	54.69106
1961	59.25827
1962	55.50823
1963	57.8581
1964	55.03633
1965	56.32881
1966	55.64758
1967	56.09748
1968	60.17228
1969	60.91449
1970	62.28944
1971	61.69378
1972	58.62723
1973	65.68589
1974	81.85429
1975	73.41462
1976	79.39966
1977	87.02339
1978	87.36297
1979	92.83221
1980	89.79098
1981	88.35974
1982	82.62609
1983	85.37863
1984	95.95778
1985	95.69164
1986	84.45175
1987	87.27916
1988	90.67079
1989	96.94954
1990	89.96716
1991	90.26598
1992	90.75206
1993	95.56547
1994	104.2717
1995	111.30031
1996	108.93293
1997	109.98459
1998	119.35909
1999	119.57282
2000	128.64286
2001	122.22781
2002	109.94083
2003	89.26033
2004	85.93485
2005	84.20595
2006	78.35188
2007	76.08452
2008	76.24325
2009	75.59174
2010	79.64481
2011	80.47312
2012	79.59441
2013	78.85509
2014	78.77829
2015	68.99029
2016	69.54123
2017	66.9543