Year	Percent
1960	34.32462
1961	34.81611
1962	45.72376
1963	53.53831
1964	46.10608
1965	52.58964
1966	73.77049
1967	84.26966
1968	72.10526
1969	54.18327
1970	60.42447
1971	54.91803
1972	58.59929
1973	56.16883
1974	59.24276
1975	56.89493
1976	67.59494
1977	68.64599
1978	86.66442
1979	99.22168
1980	114.0461
1981	105.82951
1982	101.64468
1983	100.4364
1984	92.74846
1985	92.84361
1986	79.772
1987	82.10712
1988	80.27077
1989	86.89133
1990	68.88053
1991	70.63651
1992	76.09287
1993	76.37686
1994	72.8651
1995	73.74736
1996	80.63239
1997	76.1518
1998	84.77672
1999	81.26664
2000	82.48152
2001	86.13821
2002	86.35507
2003	85.96279
2004	75.55565
2005	72.29059
2006	69.523
2007	67.79758
2008	68.35569
2009	66.58142
2010	59.57814
2011	58.45684
2012	54.9276
2013	52.8254
2014	55.14188
2015	50.10797
2016	52.67906