Year	Percent
1960	26.20437
1961	26.62755
1962	30.59831
1963	31.76064
1964	31.20426
1965	32.68561
1966	33.86228
1967	32.5805
1968	32.49711
1969	33.09065
1970	34.53181
1971	33.62256
1972	33.64886
1973	33.44112
1974	47.20319
1975	48.39174
1976	41.98136
1977	40.61788
1978	36.94811
1979	40.13206
1980	39.16268
1981	35.76885
1982	33.64087
1983	29.25509
1984	27.44451
1985	26.38532
1986	23.21328
1987	24.37143
1988	17.92375
1989	22.03272
1990	29.20438
1991	29.019
1992	31.40878
1993	31.20949
1994	31.89437
1995	32.74557
1996	34.46636
1997	34.88714
1998	36.12807
1999	35.76183
2000	34.44376
2001	30.99501
2002	29.45905
2003	28.84698
2004	30.22563
2005	101.68315
2006	103.67765
2007	103.72627
2008	101.57911
2009	90.69428
2010	94.16928
2011	104.81514
2012	105.04259
2013	82.72024
2014	74.83846
2015	61.62907
2016	54.93536
2017	51.34369