Year	Percent
1960	31.07854
1961	31.70686
1962	30.34229
1963	30.64622
1964	32.87267
1965	31.08119
1966	29.69092
1967	30.9976
1968	29.87076
1969	29.20739
1970	28.34532
1971	28.72812
1972	31.37327
1973	33.33137
1974	40.77472
1975	36.87531
1976	38.57833
1977	40.98514
1978	39.32803
1979	45.50638
1980	48.58525
1981	48.74576
1982	42.34514
1983	41.59297
1984	42.6125
1985	42.06352
1986	41.87091
1987	48.83108
1988	58.76382
1989	63.45805
1990	65.74992
1991	67.18298
1992	65.6403
1993	64.43177
1994	67.98311
1995	75.15719
1996	69.96088
1997	80.05579
1998	85.70609
1999	85.87899
2000	103.63051
2001	105.51408
2002	98.84747
2003	102.53955
2004	110.27356
2005	121.0204
2006	116.56595
2007	111.74799
2008	122.51993
2009	101.56922
2010	110.29639
2011	121.72049
2012	120.28951
2013	113.93617
2014	111.75212
2015	103.87722
2016	99.47308
2017	100.9307