Year	Percent
1960	66.88519
1961	65.06129
1962	66.94846
1963	61.20728
1964	61.49379
1965	57.20967
1966	52.08056
1967	55.58687
1968	53.88711
1969	46.82432
1970	32.67492
1971	37.65646
1972	39.90418
1973	40.1722
1974	60.95978
1975	45.43355
1976	52.07875
1977	62.09123
1978	64.58082
1979	65.64064
1980	87.40783
1981	63.05454
1982	81.45732
1983	61.41304
1984	82.10318
1985	77.97776
1986	74.29966
1987	65.36819
1988	59.43405
1989	59.75913
1990	57.23992
1991	59.56284
1992	55.70665
1993	85.93151
1994	89.86273
1995	87.05088
1996	113.98445
1997	111.67945
1998	104.89969
1999	101.15088
2000	91.74168
2001	97.95081
2002	97.84788
2003	100.34702
2004	94.69426
2005	99.36887
2006	104.64555
2007	97.26389
2008	95.91528
2009	93.81315
2010	111.59338
2011	116.85844
2012	115.2249
2013	108.45708
2014	111.07865
2015	116.81544
2016	118.40777
2017	90.29942