Year	Percent
1970	9.70613
1971	10.06124
1972	12.79578
1973	11.99104
1974	12.90937
1975	11.68784
1976	13.62243
1977	27.20726
1978	29.09176
1979	39.71382
1980	57.7257
1981	81.85325
1982	98.79383
1983	106.03917
1984	129.09555
1985	97.64929
1986	126.11398
1987	130.42017
1988	119.57638
1989	126.3663
1990	126.59176
1991	57.17365
1992	57.98768
1993	57.8683
1994	58.06458
1995	55.28805
1996	54.31664
1997	54.44999
1998	56.38392
1999	60.02998
2000	65.11363
2001	75.35477
2002	107.0458
2003	138.56469
2004	123.46972
2005	112.70975
2006	116.29348
2007	92.8056
2008	43.05172
2009	59.21796
2010	58.29644
2011	57.75843
2012	61.35341
2013	62.79067
2014	63.9023
2015	57.88934
2016	53.95388