Year	Percent
1971	55.58869
1972	54.95084
1973	58.63216
1974	61.51852
1975	65.52015
1976	69.9592
1977	71.7498
1978	70.86406
1979	74.78368
1980	77.80299
1981	81.62129
1982	84.43769
1983	88.19267
1984	90.54283
1985	91.04766
1987	93.88156
1988	95.3517
1994	95.50455
1995	93.28374
1996	92.69567
1997	95.72461
1999	96.69974
2000	96.84295
2001	97.29825
2002	97.09025
2003	96.59198
2004	96.39396
2005	100.77086
2006	100.61106
2007	100.60891
2010	99.34218
2011	106.32184
2012	110.77958
2013	111.94359
2014	112.37994
2015	115.71953
2016	108.8401
2017	104.7951