Year	Percent
1965	17.69699
1966	16.52694
1967	33.73429
1968	60.4522
1969	64.3589
1970	62.80192
1971	62.05403
1972	58.89141
1973	73.4143
1974	73.84099
1975	86.28944
1976	72.60649
1977	73.45287
1978	74.58074
1979	75.43702
1980	91.61183
1981	97.93198
1982	96.48274
1983	86.61789
1984	83.3771
1985	83.31417
1986	73.82757
1987	73.49719
1988	66.89549
1989	67.18827
1990	71.08231
1991	72.28332
1992	74.92606
1993	76.80235
1994	73.99262
1995	75.68863
1996	79.02989
1997	80.95368
1998	80.46645
1999	76.63199
2000	84.32692
2001	87.43053
2002	86.72183
2003	85.37442
2004	89.39366
2005	88.99922
2006	87.66141
2007	96.74804
2008	99.91953
2009	94.21186
2010	96.47286
2011	104.67039
2012	105.32608
2013	113.79478
2014	98.69839
2015	88.43118
2016	71.4031
2017	77.91322